An Experiment on the Limits of Quantum Electro-dynamics
DOE R&D Accomplishments [OSTI]
Barber, W. C.; Richter, B.; Panofsky, W. K. H.; O'Neill, G. K.; Gittelman, B.
1959-06-01
The limitations of previously performed or suggested electrodynamic cutoff experiments are reviewed, and an electron-electron scattering experiment to be performed with storage rings to investigate further the limits of the validity of quantum electrodynamics is described. The foreseen experimental problems are discussed, and the results of the associated calculations are given. The parameters and status of the equipment are summarized. (D.C.W.)
Quantum-projection-noise-limited interferometry with coherent atoms in a Ramsey-type setup
Doering, D.; McDonald, G.; Debs, J. E.; Figl, C.; Altin, P. A.; Bachor, H.-A.; Robins, N. P.; Close, J. D. [Australian Research Council Centre of Excellence for Quantum-Atom Optics, Australian National University, Canberra, 0200 (Australia); Department of Quantum Science, Research School of Physics and Engineering, Australian National University, Canberra, 0200 (Australia)
2010-04-15
Every measurement of the population in an uncorrelated ensemble of two-level systems is limited by what is known as the quantum projection noise limit. Here, we present quantum-projection-noise-limited performance of a Ramsey-type interferometer using freely propagating coherent atoms. The experimental setup is based on an electro-optic modulator in an inherently stable Sagnac interferometer, optically coupling the two interfering atomic states via a two-photon Raman transition. Going beyond the quantum projection noise limit requires the use of reduced quantum uncertainty (squeezed) states. The experiment described demonstrates atom interferometry at the fundamental noise level and allows the observation of possible squeezing effects in an atom laser, potentially leading to improved sensitivity in atom interferometers.
Magnetic field sensing beyond the standard quantum limit under the effect of decoherence
Matsuzaki, Yuichiro; Benjamin, Simon C.; Fitzsimons, Joseph
2011-07-15
Entangled states can potentially be used to outperform the standard quantum limit by which every classical sensor is bounded. However, entangled states are very susceptible to decoherence, and so it is not clear whether one can really create a superior sensor to classical technology via a quantum strategy which is subject to the effect of realistic noise. This paper presents an investigation of how a quantum sensor composed of many spins is affected by independent dephasing. We adopt general noise models including non-Markovian effects, and in these noise models the performance of the sensor depends crucially on the exposure time of the sensor to the field. We have found that, by choosing an appropriate exposure time within the non-Markovian time region, an entangled sensor does actually beat the standard quantum limit. Since independent dephasing is one of the most typical sources of noise in many systems, our results suggest a practical and scalable approach to beating the standard quantum limit.
Jiang, Kebei; Lee, Hwang; Gerry, Christopher C.; Dowling, Jonathan P.
2013-11-21
There has been much recent interest in quantum metrology for applications to sub-Raleigh ranging and remote sensing such as in quantum radar. For quantum radar, atmospheric absorption and diffraction rapidly degrades any actively transmitted quantum states of light, such as N00N states, so that for this high-loss regime the optimal strategy is to transmit coherent states of light, which suffer no worse loss than the linear Beer's law for classical radar attenuation, and which provide sensitivity at the shot-noise limit in the returned power. We show that coherent radar radiation sources, coupled with a quantum homodyne detection scheme, provide both longitudinal and angular super-resolution much below the Rayleigh diffraction limit, with sensitivity at shot-noise in terms of the detected photon power. Our approach provides a template for the development of a complete super-resolving quantum radar system with currently available technology.
Sanov and central limit theorems for output statistics of quantum Markov chains
Horssen, Merlijn van; Gu??, M?d?lin
2015-02-15
In this paper, we consider the statistics of repeated measurements on the output of a quantum Markov chain. We establish a large deviations result analogous to Sanov’s theorem for the multi-site empirical measure associated to finite sequences of consecutive outcomes of a classical stochastic process. Our result relies on the construction of an extended quantum transition operator (which keeps track of previous outcomes) in terms of which we compute moment generating functions, and whose spectral radius is related to the large deviations rate function. As a corollary to this, we obtain a central limit theorem for the empirical measure. Such higher level statistics may be used to uncover critical behaviour such as dynamical phase transitions, which are not captured by lower level statistics such as the sample mean. As a step in this direction, we give an example of a finite system whose level-1 (empirical mean) rate function is independent of a model parameter while the level-2 (empirical measure) rate is not.
Cohen, S.A.; Hosea, J.C.; Timberlake, J.R.
1984-10-19
A limiter with a specially contoured front face is provided. The front face of the limiter (the plasma-side face) is flat with a central indentation. In addition, the limiter shape is cylindrically symmetric so that the limiter can be rotated for greater heat distribution. This limiter shape accommodates the various power scrape-off distances lambda p, which depend on the parallel velocity, V/sub parallel/, of the impacting particles.
Cohen, Samuel A. (Hopewell, NJ); Hosea, Joel C. (Princeton, NJ); Timberlake, John R. (Allentown, NJ)
1986-01-01
A limiter with a specially contoured front face accommodates the various power scrape-off distances .lambda..sub.p, which depend on the parallel velocity, V.sub..parallel., of the impacting particles. The front face of the limiter (the plasma-side face) is flat with a central indentation. In addition, the limiter shape is cylindrically symmetric so that the limiter can be rotated for greater heat distribution.
Tucker, Jon R.; Magyar, Rudolph J.
2012-02-01
High explosives are an important class of energetic materials used in many weapons applications. Even with modern computers, the simulation of the dynamic chemical reactions and energy release is exceedingly challenging. While the scale of the detonation process may be macroscopic, the dynamic bond breaking responsible for the explosive release of energy is fundamentally quantum mechanical. Thus, any method that does not adequately describe bonding is destined to lack predictive capability on some level. Performing quantum mechanics calculations on systems with more than dozens of atoms is a gargantuan task, and severe approximation schemes must be employed in practical calculations. We have developed and tested a divide and conquer (DnC) scheme to obtain total energies, forces, and harmonic frequencies within semi-empirical quantum mechanics. The method is intended as an approximate but faster solution to the full problem and is possible due to the sparsity of the density matrix in many applications. The resulting total energy calculation scales linearly as the number of subsystems, and the method provides a path-forward to quantum mechanical simulations of millions of atoms.
Light Nuclei and HyperNuclei from Quantum Chromodynamics in the Limit of SU(3) Flavor Symmetry
Beane, S R; Cohen, S D; Detmold, W; Lin, H W; Luu, T C; Orginos, K; Parreno, A; Savage, M J
2013-02-01
The binding energies of a range of nuclei and hypernuclei with atomic number A <= 4 and strangeness |s| <= 2, including the deuteron, di-neutron, H-dibaryon, {sup 3}He, {sub {Lambda}}{sup 3}He, {sub {Lambda}}{sup 4}He, and {sub {Lambda}{Lambda}}{sup 4}He, are calculated in the limit of flavor-SU(3) symmetry at the physical strange quark mass with quantum chromodynamics (without electromagnetic interactions). The nuclear states are extracted from Lattice QCD calculations performed with n{sub f}=3 dynamical light quarks using an isotropic clover discretization of the quark-action in three lattice volumes of spatial extent L ~ 3.4 fm, 4.5 fm and 6.7 fm, and with a single lattice spacing b ~ 0.145 fm.
Danel, J.-F.; Blottiau, P.; Kazandjian, L.; Piron, R.; Torrent, M.
2014-10-15
The applicability of quantum molecular dynamics to the calculation of the equation of state of a dense plasma is limited at high temperature by computational cost. Orbital-free molecular dynamics, based on a semiclassical approximation and possibly on a gradient correction, is a simulation method available at high temperature. For a high-Z element such as lutetium, we examine how orbital-free molecular dynamics applied to the equation of state of a dense plasma can be regarded as the limit of quantum molecular dynamics at high temperature. For the normal mass density and twice the normal mass density, we show that the pressures calculated with the quantum approach converge monotonically towards those calculated with the orbital-free approach; we observe a faster convergence when the orbital-free approach includes the gradient correction. We propose a method to obtain an equation of state reproducing quantum molecular dynamics results up to high temperatures where this approach cannot be directly implemented. With the results already obtained for low-Z plasmas, the present study opens the way for reproducing the quantum molecular dynamics pressure for all elements up to high temperatures.
Teymurazyan, A.; Rowlands, J. A.; Thunder Bay Regional Research Institute , Thunder Bay P7A 7T1; Department of Radiation Oncology, University of Toronto, Toronto M5S 3E2 ; Pang, G.
2014-04-15
Purpose: Electronic Portal Imaging Devices (EPIDs) have been widely used in radiation therapy and are still needed on linear accelerators (Linacs) equipped with kilovoltage cone beam CT (kV-CBCT) or MRI systems. Our aim is to develop a new high quantum efficiency (QE) ?erenkov Portal Imaging Device (CPID) that is quantum noise limited at dose levels corresponding to a single Linac pulse. Methods: Recently a new concept of CPID for MV x-ray imaging in radiation therapy was introduced. It relies on ?erenkov effect for x-ray detection. The proposed design consisted of a matrix of optical fibers aligned with the incident x-rays and coupled to an active matrix flat panel imager (AMFPI) for image readout. A weakness of such design is that too few ?erenkov light photons reach the AMFPI for each incident x-ray and an AMFPI with an avalanche gain is required in order to overcome the readout noise for portal imaging application. In this work the authors propose to replace the optical fibers in the CPID with light guides without a cladding layer that are suspended in air. The air between the light guides takes on the role of the cladding layer found in a regular optical fiber. Since air has a significantly lower refractive index (?1 versus 1.38 in a typical cladding layer), a much superior light collection efficiency is achieved. Results: A Monte Carlo simulation of the new design has been conducted to investigate its feasibility. Detector quantities such as quantum efficiency (QE), spatial resolution (MTF), and frequency dependent detective quantum efficiency (DQE) have been evaluated. The detector signal and the quantum noise have been compared to the readout noise. Conclusions: Our studies show that the modified new CPID has a QE and DQE more than an order of magnitude greater than that of current clinical systems and yet a spatial resolution similar to that of current low-QE flat-panel based EPIDs. Furthermore it was demonstrated that the new CPID does not require an avalanche gain in the AMFPI and is quantum noise limited at dose levels corresponding to a single Linac pulse.
Quantum discord with weak measurements
Singh, Uttam Pati, Arun Kumar
2014-04-15
Weak measurements cause small change to quantum states, thereby opening up the possibility of new ways of manipulating and controlling quantum systems. We ask, can weak measurements reveal more quantum correlation in a composite quantum state? We prove that the weak measurement induced quantum discord, called as the “super quantum discord”, is always larger than the quantum discord captured by the strong measurement. Moreover, we prove the monotonicity of the super quantum discord as a function of the measurement strength and in the limit of strong projective measurement the super quantum discord becomes the normal quantum discord. We find that unlike the normal discord, for pure entangled states, the super quantum discord can exceed the quantum entanglement. Our results provide new insights on the nature of quantum correlation and suggest that the notion of quantum correlation is not only observer dependent but also depends on how weakly one perturbs the composite system. We illustrate the key results for pure as well as mixed entangled states. -- Highlights: •Introduced the role of weak measurements in quantifying quantum correlation. •We have introduced the notion of the super quantum discord (SQD). •For pure entangled state, we show that the SQD exceeds the entanglement entropy. •This shows that quantum correlation depends not only on observer but also on measurement strength.
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Quantum Institute Quantum Institute A new research frontier awaits! Our door is open and we thrive on mutually beneficial partnerships, collaborations that drive innovations and new technologies. Contact Leader Malcolm Boshier (505) 665-8892 Email Two of LANL's most successful quantum technology initiatives: quantum cryptography and the race for quantum computer The area of quantum information, science, and technology is rapidly evolving, with important applications in the areas of quantum
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Fan, Wenjiang; Lawrie, Benjamin J.; Pooser, Raphael C.
2015-11-04
Surface plasmon resonance (SPR) sensors can reach the quantum noise limit of the optical readout field in various configurations. We demonstrate that two-mode intensity squeezed states produce a further enhancement in sensitivity compared with a classical optical readout when the quantum noise is used to transduce an SPR sensor signal in the Kretschmann configuration. The quantum noise reduction between the twin beams when incident at an angle away from the plasmonic resonance, combined with quantum noise resulting from quantum anticorrelations when on resonance, results in an effective SPR-mediated modulation that yields a measured sensitivity 5 dB better than that withmoreÂ Â» a classical optical readout in this configuration. Furthermore, the theoretical potential of this technique points to resolving particle concentrations with more accuracy than is possible via classical approaches to optical transduction.Â«Â less
Fan, Wenjiang; Lawrie, Benjamin J.; Pooser, Raphael C.
2015-11-04
Surface plasmon resonance (SPR) sensors can reach the quantum noise limit of the optical readout field in various configurations. We demonstrate that two-mode intensity squeezed states produce a further enhancement in sensitivity compared with a classical optical readout when the quantum noise is used to transduce an SPR sensor signal in the Kretschmann configuration. The quantum noise reduction between the twin beams when incident at an angle away from the plasmonic resonance, combined with quantum noise resulting from quantum anticorrelations when on resonance, results in an effective SPR-mediated modulation that yields a measured sensitivity 5 dB better than that with a classical optical readout in this configuration. Furthermore, the theoretical potential of this technique points to resolving particle concentrations with more accuracy than is possible via classical approaches to optical transduction.
Castagnoli, G. )
1991-08-10
This paper reports that current conceptions of quantum mechanical computers inherit from conventional digital machines two apparently interacting features, machine imperfection and temporal development of the computational process. On account of machine imperfection, the process would become ideally reversible only in the limiting case of zero speed. Therefore the process is irreversible in practice and cannot be considered to be a fundamental quantum one. By giving up classical features and using a linear, reversible and non-sequential representation of the computational process - not realizable in classical machines - the process can be identified with the mathematical form of a quantum steady state. This form of steady quantum computation would seem to have an important bearing on the notion of cognition.
Continuous-time quantum walks on star graphs
Salimi, S.
2009-06-15
In this paper, we investigate continuous-time quantum walk on star graphs. It is shown that quantum central limit theorem for a continuous-time quantum walk on star graphs for N-fold star power graph, which are invariant under the quantum component of adjacency matrix, converges to continuous-time quantum walk on K{sub 2} graphs (complete graph with two vertices) and the probability of observing walk tends to the uniform distribution.
Quantum chaos in the Lorenz equations with symmetry breaking
Sarkar, S.; Satchell, J.S.
1987-01-01
The role of phase diffusion for quantum chaos in the quantum-mechanical model of the laser in the Haken limit is discussed. Fractal properties of the support of the asymptotic attracting probability distribution for the system are studied.
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Quantum technology and its applications
Boshier, Malcolm; Berkeland, Dana; Govindan, Tr; Abo - Shaeer, Jamil
2010-12-10
Quantum states of matter can be exploited as high performance sensors for measuring time, gravity, rotation, and electromagnetic fields, and quantum states of light provide powerful new tools for imaging and communication. Much attention is being paid to the ultimate limits of this quantum technology. For example, it has already been shown that exotic quantum states can be used to measure or image with higher precision or higher resolution or lower radiated power than any conventional technologies, and proof-of-principle experiments demonstrating measurement precision below the standard quantum limit (shot noise) are just starting to appear. However, quantum technologies have another powerful advantage beyond pure sensing performance that may turn out to be more important in practical applications: the potential for building devices with lower size/weight/power (SWaP) and cost requirements than existing instruments. The organizers of Quantum Technology Applications Workshop (QTAW) have several goals: (1) Bring together sponsors, researchers, engineers and end users to help build a stronger quantum technology community; (2) Identify how quantum systems might improve the performance of practical devices in the near- to mid-term; and (3) Identify applications for which more long term investment is necessary to realize improved performance for realistic applications. To realize these goals, the QTAW II workshop included fifty scientists, engineers, managers and sponsors from academia, national laboratories, government and the private-sector. The agenda included twelve presentations, a panel discussion, several breaks for informal exchanges, and a written survey of participants. Topics included photon sources, optics and detectors, squeezed light, matter waves, atomic clocks and atom magnetometry. Corresponding applications included communication, imaging, optical interferometry, navigation, gravimetry, geodesy, biomagnetism, and explosives detection. Participants considered the physics and engineering of quantum and conventional technologies, and how quantum techniques could (or could not) overcome limitations of conventional systems. They identified several auxiliary technologies that needed to be further developed in order to make quantum technology more accessible. Much of the discussion also focused on specific applications of quantum technology and how to push the technology into broader communities, which would in turn identify new uses of the technology. Since our main interest is practical improvement of devices and techniques, we take a liberal definition of 'quantum technology': a system that utilizes preparation and measurement of a well-defined coherent quantum state. This nomenclature encompasses features broader than entanglement, squeezing or quantum correlations, which are often more difficult to utilize outside of a laboratory environment. Still, some applications discussed in the workshop do take advantage of these 'quantum-enhanced' features. They build on the more established quantum technologies that are amenable to manipulation at the quantum level, such as atom magnetometers and atomic clocks. Understanding and developing those technologies through traditional engineering will clarify where quantum-enhanced features can be used most effectively, in addition to providing end users with improved devices in the near-term.
Sandia Energy - Quantum Optics
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Quantum Optics Home Energy Research EFRCs Solid-State Lighting Science EFRC Quantum Optics Quantum OpticsTara Camacho-Lopez2015-03-30T16:37:03+00:00 Quantum Optics with a Single...
Lincoln, Don
2014-10-24
The laws of quantum mechanics and relativity are quite perplexing however it is when the two theories are merged that things get really confusing. This combined theory predicts that empty space isn’t empty at all – it’s a seething and bubbling cauldron of matter and antimatter particles springing into existence before disappearing back into nothingness. Scientists call this complicated state of affairs “quantum foam.” In this video, Fermilab’s Dr. Don Lincoln discusses this mind-bending idea and sketches some of the experiments that have convinced scientists that this crazy prediction is actually true.
A semiclassical study of quantum maps
Guo, Y.
1992-01-01
The study of the behavior of quantum systems whose classical limit exhibits chaos defines the problem of quantum chaos. One would naturally ask how quantum mechanics approaches the classical limit [h bar] = 0, and how the chaotic motion in classical systems manifests itself in the corresponding quantum counterparts. Semiclassical mechanics is the bridge between quantum mechanics and classical mechanics. For studying the quantum mechanics corresponding to generic classical motion it is desirable to use the simplest possible model. The model system the authors use is the kicked rotator. Detailed computations of both classical and quantum mechanics are feasible for this system. The relationship between invariant classical phase space structures and quantum eigenfunctions has been the focus of recent semiclassical studies. The authors study the eigenstates of the quantum standard map associated with both integrable and non-integrable regions in classical phase space. The coherent-state representation is used to make the correspondence between the quantum eigenstates and the classical phase space structure. The importance of periodic orbits in the quantum eigenstates of classically chaotic Hamiltonians has become a popular topic in study of semiclassical limits of the systems. Periodic orbits arise without any assumption in the trace formula developed by Gutzwiller. The authors calculate the semiclassical coherent-state propagator. Since computing all the complex stationary orbits is not practical, the authors make a further assumption which the authors call the periodic point dominance (PPD). The authors present arguments and evidence to show that the PPD approximation works well in hard chaos regions where the full semiclassical approximation is not practical to use. The method fails in some boundary regions where both stable and unstable points are present, but the full semiclassical approximation is not a much better method than the PPD in many situations.
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Stapp, Henry
2011-11-10
Robert Griffiths has recently addressed, within the framework of a ‘consistent quantum theory’ (CQT) that he has developed, the issue of whether, as is often claimed, quantum mechanics entails a need for faster-than-light transfers of information over long distances. He argues, on the basis of his examination of certain arguments that claim to demonstrate the existence of such nonlocal influences, that such influences do not exist. However, his examination was restricted mainly to hidden-variable-based arguments that include in their premises some essentially classical-physics-type assumptions that are fundamentally incompatible with the precepts of quantum physics. One cannot logically prove properties of a system by attributing to the system properties alien to that system. Hence Griffiths’ rejection of hidden-variable-based proofs is logically warranted. Griffiths mentions the existence of a certain alternative proof that does not involve hidden variables, and that uses only macroscopically described observable properties. He notes that he had examined in his book proofs of this general kind, and concluded that they provide no evidence for nonlocal influences. But he did not examine the particular proof that he cites. An examination of that particular proof by the method specified by his ‘consistent quantum theory’ shows that the cited proof is valid within that restrictive framework. This necessary existence, within the ‘consistent’ framework, of long range essentially instantaneous influences refutes the claim made by Griffiths that his ‘consistent’ framework is superior to the orthodox quantum theory of von Neumann because it does not entail instantaneous influences. An added section responds to Griffiths’ reply, which cites a litany of ambiguities that seem to restrict, devastatingly, the scope of his CQT formalism, apparently to buttress his claim that my use of that formalism to validate the nonlocality theorem is flawed. But the vagaries that he cites do not upset the proof in question. It is show here in detail why the precise statement of this theorem justifies the specified application of CQT. It is also shown, in response to his challenge, why a putative proof of locality that he has proposed is not valid.
Quantum Field Theory & Gravity
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begin? What is its large scale structure and evolution? How can gravity be unified with quantum mechanics and the Standard Model? Quantum Field Theory, Gravity & Cosmology There...
Lattice Quantum Chromodynamics
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Lattice Quantum Chromodynamics Lattice Quantum Chromodynamics QCD-BU.jpg Key Challenges: Although the QCD theory has been extensively tested at at high energies, at low energies or...
Electrical resistivity as quantum chaos
Laughlin, R.B.
1987-08-01
The physics of quantum transport is re-examined as a problem in quantum chaos. It is proposed that the ''random potential'' in which electrons in dirty metals move is not random at all, but rather any potential inducing the electron motion to be chaotic. The Liapunov characteristic exponent of classical electron motion in this potential is identified with the collision rate l/tau appearing in Ohm's law. A field theory for chaotic systems, analogous to that used to describe dirty metals, is developed and used to investigate the quantum Sinai billiard problem. It is shown that a noninteracting degenerate electron gas moving in this potential exhibits Drude conductivity in the limit h-bar ..-->.. 0. 15 refs., 4 figs.
Modeling of the quantum dot filling and the dark current of quantum dot infrared photodetectors
Ameen, Tarek A.; El-Batawy, Yasser M.; Abouelsaood, A. A.
2014-02-14
A generalized drift-diffusion model for the calculation of both the quantum dot filling profile and the dark current of quantum dot infrared photodetectors is proposed. The confined electrons inside the quantum dots produce a space-charge potential barrier between the two contacts, which controls the quantum dot filling and limits the dark current in the device. The results of the model reasonably agree with a published experimental work. It is found that increasing either the doping level or the temperature results in an exponential increase of the dark current. The quantum dot filling turns out to be nonuniform, with a dot near the contacts containing more electrons than one in the middle of the device where the dot occupation approximately equals the number of doping atoms per dot, which means that quantum dots away from contacts will be nearly unoccupied if the active region is undoped.
Thermodynamic universality of quantum Carnot engines
Gardas, Bart?omiej; Deffner, Sebastian
2015-10-12
The Carnot statement of the second law of thermodynamics poses an upper limit on the efficiency of all heat engines. Recently, it has been studied whether generic quantum features such as coherence and quantum entanglement could allow for quantum devices with efficiencies larger than the Carnot efficiency. The present study shows that this is not permitted by the laws of thermodynamic —independent of the model. We will show that rather the definition of heat has to be modified to account for the thermodynamic cost of maintaining non-Gibbsian equilibrium states. As a result, our theoretical findings are illustrated for two experimentally relevant examples.
Thermodynamic universality of quantum Carnot engines
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Gardas, BartĹ‚omiej; Deffner, Sebastian
2015-10-12
The Carnot statement of the second law of thermodynamics poses an upper limit on the efficiency of all heat engines. Recently, it has been studied whether generic quantum features such as coherence and quantum entanglement could allow for quantum devices with efficiencies larger than the Carnot efficiency. The present study shows that this is not permitted by the laws of thermodynamic â€”independent of the model. We will show that rather the definition of heat has to be modified to account for the thermodynamic cost of maintaining non-Gibbsian equilibrium states. As a result, our theoretical findings are illustrated for two experimentallymoreÂ Â» relevant examples.Â«Â less
Quantum Fuel Systems Technologies Worldwide Inc Quantum Technologies...
Fuel Systems Technologies Worldwide Inc Quantum Technologies Jump to: navigation, search Name: Quantum Fuel Systems Technologies Worldwide Inc (Quantum Technologies) Place: Irvine,...
Huang, Liang; Lai Yingcheng; Ferry, David K.; Goodnick, Stephen M.; Akis, Richard
2009-07-31
The concentrations of wave functions about classical periodic orbits, or quantum scars, are a fundamental phenomenon in physics. An open question is whether scarring can occur in relativistic quantum systems. To address this question, we investigate confinements made of graphene whose classical dynamics are chaotic and find unequivocal evidence of relativistic quantum scars. The scarred states can lead to strong conductance fluctuations in the corresponding open quantum dots via the mechanism of resonant transmission.
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Quantum ESPRESSO/PWscf Quantum ESPRESSO/PWscf Description Quantum ESPRESSO is an integrated suite of computer codes for electronic structure calculations and materials modeling at the nanoscale. It builds on the electronic structure codes PWscf, PHONON, CP90, FPMD, and Wannier. It is based on density-functional theory, plane waves, and pseudopotentials (both norm-conserving and ultrasoft). How to Access Quantum ESPRESSO NERSC uses modules to manage access to software. To use the default version
Golovashkin, A. I.; Zherikhina, L. N. Tskhovrebov, A. M.; Izmailov, G. N.; Ozolin, V. V.
2010-08-15
When comparing the operation of a superfluid helium matter wave quantum interferometer (He SQUID) with that of an ordinary direct-current quantum interferometer (dc SQUID), we estimate their resolution limitation that correspond to quantum fluctuations. An alternative mode of operation of the interferometer as a unified macroquantum system is considered.
Deviation from the Knudsen law on quantum gases
Babac, Gulru
2014-12-09
Gas flow in micro/nano scale systems has been generally studied for the Maxwell gases. In the limits of very low temperature and very confined domains, the Maxwellian approximation can break down and the quantum character of the gases becomes important. In these cases, Knudsen law, which is one of the important equations to analyze rarefied gas flows is invalid and should be reanalyzed for quantum gases. In this work, the availability of quantum gas conditions in the high Knudsen number cases is discussed and Knudsen law is analyzed for quantum gases.
Scalable optical quantum computer
Manykin, E A; Mel'nichenko, E V [Institute for Superconductivity and Solid-State Physics, Russian Research Centre 'Kurchatov Institute', Moscow (Russian Federation)
2014-12-31
A way of designing a scalable optical quantum computer based on the photon echo effect is proposed. Individual rare earth ions Pr{sup 3+}, regularly located in the lattice of the orthosilicate (Y{sub 2}SiO{sub 5}) crystal, are suggested to be used as optical qubits. Operations with qubits are performed using coherent and incoherent laser pulses. The operation protocol includes both the method of measurement-based quantum computations and the technique of optical computations. Modern hybrid photon echo protocols, which provide a sufficient quantum efficiency when reading recorded states, are considered as most promising for quantum computations and communications. (quantum computer)
Anisotropic Fermi Surface and Quantum Limit Transport in High...
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Chenglong ; Wang, Huichao ; Wang, Junfeng ; Lin, Ziquan ; Xing, Ying ; Lu, Hong ; Liu, Jun ; Wang, Yong ; Brombosz, Scott M. ; Xiao, Zhili ; Jia, Shuang ; Xie, X. C. ; Wang, Jian...
Quest for the quantum limit in three dimensional metals
Brooks, J.S.; Qualls, J.S.; Engel, L.W. [Florida State Univ., Tallahassee, FL (United States)] [and others
1996-11-01
The purpose of this work is to exploit ultra-high, flux compression type magnetic fields to achieve magnetic energies which are on the same or greater scale of the electronic structure in metallic systems. Under such conditions a metal. may become an insulator, may acquire a completely new electronic structure, or may develop novel configurations of electronic order. In this paper we consider experiments on quasi-two dimensional molecular conductors in both non-destructive pulsed fields to 60 T and in destructive flux compression fields to 700 T at low temperatures. New results on the molecular conductors {alpha}-(BEDT-TTF) {sub 2}NH{sub 4}Hg(SCN){sub 4} and (TMTSF){sub 2}ClO{sub 4} are discussed in experiments up to 60 T at low temperatures, and preliminary results on {alpha}-(BEDT-TTF){sub 2}NH{sub 4}Hg(SON){sub 4} in the 700 T MC1 series flux compression generators are presented. We argue that true direct dc electrical transport measurements in these materials at low temperatures up to 700 T appear to be within reach.
Dynamically consistent method for mixed quantum-classical simulations: A semiclassical approach
Antipov, Sergey V.; Ye, Ziyu; Ananth, Nandini
2015-05-14
We introduce a new semiclassical (SC) framework, the Mixed Quantum-Classical Initial Value Representation (MQC-IVR), that can be tuned to reproduce existing quantum-limit and classical-limit SC approximations to quantum real-time correlation functions. Applying a modified Filinov transformation to a quantum-limit SC formulation leads to the association of a Filinov parameter with each degree of freedom in the system; varying this parameter from zero to infinity controls the extent of quantization of the corresponding mode. The resulting MQC-IVR expression provides a consistent dynamic framework for mixed quantum-classical simulations and we demonstrate its numerical accuracy in the calculation of real-time correlation functions for a model 1D system and a model 2D system over the full range of quantum- to classical-limit behaviors.
Audenaert, Koenraad M. R.
2014-11-15
In this paper, we study the quantum generalisation of the skew divergence, which is a dissimilarity measure between distributions introduced by Lee in the context of natural language processing. We provide an in-depth study of the quantum skew divergence, including its relation to other state distinguishability measures. Finally, we present a number of important applications: new continuity inequalities for the quantum Jensen-Shannon divergence and the Holevo information, and a new and short proof of Bravyi's Small Incremental Mixing conjecture.
Heller, E.J. (Los Alamos National Lab., Albuquerque, NM); Davis, M.J.
1982-06-10
This paper reviews some of the opinions on quantum chaos put forth at the 1981 American Conference on Theoretical Chemistry and presents evidence to support the author's point of view. The degree of correspondence between classical and quantum onset and extent of chaos differs markedly according to the definition adopted for quantum chaos. At one extreme, a quantum generalization of the classical Kolmolgorov entropy which give zero entrophy for quantum systems with a discrete spectrum regardless of the classical properties, was a suitable foundation for the definition of quantum chaos. At the other, the quantum phase space definition shows generally excellent correspondence to the classical phase space measures. The authors preferred this approach. Another point of controversy is the question of whether the spectrum of energy levels (or its variation with some parameter of the Hamiltonian) is enough to characterize the quantum chaos (or lack of it), or whether more information is needed (i.e., eigenfunctions). The authors conclude that one does not want to rely upon eigenvalues alone to characterize the degree of chaos in the quantum dynamics.
Comparison of the attempts of quantum discord and quantum entanglement...
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Subject: 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ALGORITHMS; CAPTURE; ENTROPY; MIXED STATES; PURE STATES; QUANTUM ENTANGLEMENT MATHEMATICAL LOGIC; PHYSICAL PROPERTIES; ...
Lee, Sang-Bong
1993-09-01
Quantum manifestation of classical chaos has been one of the extensively studied subjects for more than a decade. Yet clear understanding of its nature still remains to be an open question partly due to the lack of a canonical definition of quantum chaos. The classical definition seems to be unsuitable in quantum mechanics partly because of the Heisenberg quantum uncertainty. In this regard, quantum chaos is somewhat misleading and needs to be clarified at the very fundamental level of physics. Since it is well known that quantum mechanics is more fundamental than classical mechanics, the quantum description of classically chaotic nature should be attainable in the limit of large quantum numbers. The focus of my research, therefore, lies on the correspondence principle for classically chaotic systems. The chaotic damped driven pendulum is mainly studied numerically using the split operator method that solves the time-dependent Schroedinger equation. For classically dissipative chaotic systems in which (multi)fractal strange attractors often emerge, several quantum dissipative mechanisms are also considered. For instance, Hoover`s and Kubo-Fox-Keizer`s approaches are studied with some computational analyses. But the notion of complex energy with non-Hermiticity is extensively applied. Moreover, the Wigner and Husimi distribution functions are examined with an equivalent classical distribution in phase-space, and dynamical properties of the wave packet in configuration and momentum spaces are also explored. The results indicate that quantum dynamics embraces classical dynamics although the classicalquantum correspondence fails to be observed in the classically chaotic regime. Even in the semi-classical limits, classically chaotic phenomena would eventually be suppressed by the quantum uncertainty.
Quantum physics and human values
Stapp, H.P.
1989-09-01
This report discusses the following concepts: the quantum conception of nature; the quantum conception of man; and the impact upon human values. (LSP).
Physical interpretation of Jeans instability in quantum plasmas
Akbari-Moghanjoughi, M.
2014-08-15
In this paper, we use the quantum hydrodynamics and its hydrostatic limit to investigate the newly posed problem of Jeans instability in quantum plasmas from a different point of view in connection with the well-known Chandrasekhar mass-limit on highly collapsed degenerate stellar configurations. It is shown that the hydrodynamic stability of a spherically symmetric uniform quantum plasma with a given fixed mass is achieved by increase in its mass-density or decrease in the radius under the action of gravity. It is also remarked that for masses beyond the limiting Jeans-mass, the plasma becomes completely unstable and the gravitational collapse would proceed forever. This limiting mass is found to depend strongly on the composition of the quantum plasma and the atomic-number of the constituent ions, where it is observed that heavier elements rather destabilize the quantum plasma hydrodynamically. It is also shown that the Chandrasekhar mass-limit for white dwarf stars can be directly obtained from the hydrostatic limit of our model.
Vukmirovic, Nenad; Wang, Lin-Wang
2009-11-10
This review covers the description of the methodologies typically used for the calculation of the electronic structure of self-assembled and colloidal quantum dots. These are illustrated by the results of their application to a selected set of physical effects in quantum dots.
Micic, O.I.; Jones, K.M.; Cahill, A.; Nozik, A.J.
1998-12-03
Solid films consisting of close-packed arrays of InP quantum dots have been prepared by slowly evaporating colloidal solutions of InP quantum dots. The diameters of the quantum dots were controlled to be between about 30 to 60 {angstrom}; size-selective precipitation yielded a size distribution of about 10% about the mean diameter. The arrays show regions of hexagonal order, as well as disordered regions. Oxide layers can form irreversibly on the quantum dot surface and limit the effectiveness of the size-selective precipitation. Photoluminescence spectra obtained from close-packed films of InP quantum dots formed from quantum dots with a single mean diameter and from a mixture of two quantum dot sizes show that energy transfer occurs from the photoexcited smaller quantum dots to the larger quantum dots. The efficiency of this energy transfer process is high.
Quantum histories without contrary inferences
Losada, Marcelo; Laura, Roberto
2014-12-15
In the consistent histories formulation of quantum theory it was shown that it is possible to retrodict contrary properties. We show that this problem do not appear in our formalism of generalized contexts for quantum histories. - Highlights: • We prove ordinary quantum mechanics has no contrary properties. • Contrary properties in consistent histories are reviewed. • We prove generalized contexts for quantum histories have no contrary properties.
Direct measure of quantum correlation
Yu, Chang-shui [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Zhao, Haiqing [School of Science, Dalian Jiaotong University, Dalian 116028 (China)
2011-12-15
The quantumness of the correlation known as quantum correlation is usually measured by quantum discord. So far various quantum discords can be roughly understood as indirect measure by some special discrepancy of two quantities. We present a direct measure of quantum correlation by revealing the difference between the structures of classically and quantum correlated states. Our measure explicitly includes the contributions of the inseparability and local nonorthogonality of the eigenvectors of a density matrix. Besides its relatively easy computability, our measure can provide a unified understanding of quantum correlation of all the present versions.
The promise of quantum simulation
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Muller, Richard P.; Blume-Kohout, Robin
2015-07-21
In this study, quantum simulations promise to be one of the primary applications of quantum computers, should one be constructed. This article briefly summarizes the history of quantum simulation in light of the recent result of Wang and co-workers, demonstrating calculation of the ground and excited states for a HeH+ molecule, and concludes with a discussion of why this and other recent progress in the field suggest that quantum simulations of quantum chemistry have a bright future.
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing...
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based on molecular magnets that may make them suitable as qubits for quantum computers. Chemistry Aids Quantum Computing Quantum bits or qubits are the fundamental...
Sandia Energy - 'Giant' Nanocrystal Quantum Dots
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'Giant' Nanocrystal Quantum Dots Home Energy Research EFRCs Solid-State Lighting Science EFRC 'Giant' Nanocrystal Quantum Dots 'Giant' Nanocrystal Quantum DotsTara...
Turbocharging Quantum Tomography.
Blume-Kohout, Robin J; Gamble, John King,; Nielsen, Erik; Maunz, Peter Lukas Wilhelm; Scholten, Travis L.; Rudinger, Kenneth Michael
2015-01-01
Quantum tomography is used to characterize quantum operations implemented in quantum information processing (QIP) hardware. Traditionally, state tomography has been used to characterize the quantum state prepared in an initialization procedure, while quantum process tomography is used to characterize dynamical operations on a QIP system. As such, tomography is critical to the development of QIP hardware (since it is necessary both for debugging and validating as-built devices, and its results are used to influence the next generation of devices). But tomography su %7C ers from several critical drawbacks. In this report, we present new research that resolves several of these flaws. We describe a new form of tomography called gate set tomography (GST), which unifies state and process tomography, avoids prior methods critical reliance on precalibrated operations that are not generally available, and can achieve unprecedented accuracies. We report on theory and experimental development of adaptive tomography protocols that achieve far higher fidelity in state reconstruction than non-adaptive methods. Finally, we present a new theoretical and experimental analysis of process tomography on multispin systems, and demonstrate how to more e %7C ectively detect and characterize quantum noise using carefully tailored ensembles of input states.
Single-dot optical emission from ultralow density well-isolated InP quantum dots
Ugur, A.; Hatami, F.; Masselink, W. T.; Vamivakas, A. N.; Lombez, L.; Atatuere, M.
2008-10-06
We demonstrate a straightforward way to obtain single well-isolated quantum dots emitting in the visible part of the spectrum and characterize the optical emission from single quantum dots using this method. Self-assembled InP quantum dots are grown using gas-source molecular-beam epitaxy over a wide range of InP deposition rates, using an ultralow growth rate of about 0.01 atomic monolayers/s, a quantum-dot density of 1 dot/{mu}m{sup 2} is realized. The resulting isolated InP quantum dots embedded in an InGaP matrix are individually characterized without the need for lithographical patterning and masks on the substrate. Such low-density quantum dots show excitonic emission at around 670 nm with a linewidth limited by instrument resolution. This system is applicable as a single-photon source for applications such as quantum cryptography.
National Nuclear Security Administration (NNSA)
Detection System (USNDS), which monitors compliance with the international Limited Test Ban Treaty (LTBT). The LTBT, signed by 108 countries, prohibits nuclear testing in the...
Quantum theory and Einstein's general relativity
v. Borzeszkowski, H.; Treder, H.
1982-11-01
We dicusss the meaning and prove the accordance of general relativity, wave mechanics, and the quantization of Einstein's gravitation equations themselves. Firstly, we have the problem of the influence of gravitational fields on the de Broglie waves, which influence is in accordance with Einstein's weak principle of equivalence and the limitation of measurements given by Heisenberg's uncertainty relations. Secondly, the quantization of the gravitational fields is a ''quantization of geometry.'' However, classical and quantum gravitation have the same physical meaning according to limitations of measurements given by Einstein's strong principle of equivalence and the Heisenberg uncertainties for the mechanics of test bodies.
Some properties of correlations of quantum lattice systems in thermal equilibrium
Fröhlich, Jürg; Ueltschi, Daniel
2015-05-15
Simple proofs of uniqueness of the thermodynamic limit of KMS states and of the decay of equilibrium correlations are presented for a large class of quantum lattice systems at high temperatures. New quantum correlation inequalities for general Heisenberg models are described. Finally, a simplified derivation of a general result on power-law decay of correlations in 2D quantum lattice systems with continuous symmetries is given, extending results of McBryan and Spencer for the 2D classical XY model.
Random unitary maps for quantum state reconstruction
Merkel, Seth T. [Institute for Quantum Computing, Waterloo, Ontario N2L 3G1 (Canada); Riofrio, Carlos A.; Deutsch, Ivan H. [Center for Quantum Information and Control (CQuIC), Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico, 87131 (United States); Flammia, Steven T. [Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5 (Canada); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States)
2010-03-15
We study the possibility of performing quantum state reconstruction from a measurement record that is obtained as a sequence of expectation values of a Hermitian operator evolving under repeated application of a single random unitary map, U{sub 0}. We show that while this single-parameter orbit in operator space is not informationally complete, it can be used to yield surprisingly high-fidelity reconstruction. For a d-dimensional Hilbert space with the initial observable in su(d), the measurement record lacks information about a matrix subspace of dimension {>=}d-2 out of the total dimension d{sup 2}-1. We determine the conditions on U{sub 0} such that the bound is saturated, and show they are achieved by almost all pseudorandom unitary matrices. When we further impose the constraint that the physical density matrix must be positive, we obtain even higher fidelity than that predicted from the missing subspace. With prior knowledge that the state is pure, the reconstruction will be perfect (in the limit of vanishing noise) and for arbitrary mixed states, the fidelity is over 0.96, even for small d, and reaching F>0.99 for d>9. We also study the implementation of this protocol based on the relationship between random matrices and quantum chaos. We show that the Floquet operator of the quantum kicked top provides a means of generating the required type of measurement record, with implications on the relationship between quantum chaos and information gain.
Suppression of quantum chaos in a quantum computer hardware
Lages, J.; Shepelyansky, D. L. [Laboratoire de Physique Theorique, UMR 5152 du CNRS, Universite Paul Sabatier, 31062 Toulouse Cedex 4 (France)
2006-08-15
We present numerical and analytical studies of a quantum computer proposed by the Yamamoto group in Phys. Rev. Lett. 89, 017901 (2002). The stable and quantum chaos regimes in the quantum computer hardware are identified as a function of magnetic field gradient and dipole-dipole couplings between qubits on a square lattice. It is shown that a strong magnetic field gradient leads to suppression of quantum chaos.
McBranch, Duncan W. (Santa Fe, NM); Mattes, Benjamin R. (Santa Fe, NM); Koskelo, Aaron C. (Los Alamos, NM); Heeger, Alan J. (Santa Barbara, CA); Robinson, Jeanne M. (Los Alamos, NM); Smilowitz, Laura B. (Los Alamos, NM); Klimov, Victor I. (Los Alamos, NM); Cha, Myoungsik (Goleta, CA); Sariciftci, N. Serdar (Santa Barbara, CA); Hummelen, Jan C. (Groningen, NL)
1998-01-01
Optical limiting materials. Methanofullerenes, fulleroids and/or other fullerenes chemically altered for enhanced solubility, in liquid solution, and in solid blends with transparent glass (SiO.sub.2) gels or polymers, or semiconducting (conjugated) polymers, are shown to be useful as optical limiters (optical surge protectors). The nonlinear absorption is tunable such that the energy transmitted through such blends saturates at high input energy per pulse over a wide range of wavelengths from 400-1100 nm by selecting the host material for its absorption wavelength and ability to transfer the absorbed energy into the optical limiting composition dissolved therein. This phenomenon should be generalizable to other compositions than substituted fullerenes.
Maunz, Peter Lukas Wilhelm; Sterk, Jonathan David; Lobser, Daniel; Parekh, Ojas D.; Ryan-Anderson, Ciaran
2016-01-01
In recent years, advanced network analytics have become increasingly important to na- tional security with applications ranging from cyber security to detection and disruption of ter- rorist networks. While classical computing solutions have received considerable investment, the development of quantum algorithms to address problems, such as data mining of attributed relational graphs, is a largely unexplored space. Recent theoretical work has shown that quan- tum algorithms for graph analysis can be more efficient than their classical counterparts. Here, we have implemented a trapped-ion-based two-qubit quantum information proces- sor to address these goals. Building on Sandia's microfabricated silicon surface ion traps, we have designed, realized and characterized a quantum information processor using the hyperfine qubits encoded in two 171 Yb + ions. We have implemented single qubit gates using resonant microwave radiation and have employed Gate set tomography (GST) to characterize the quan- tum process. For the first time, we were able to prove that the quantum process surpasses the fault tolerance thresholds of some quantum codes by demonstrating a diamond norm distance of less than 1 . 9 x 10 [?] 4 . We used Raman transitions in order to manipulate the trapped ions' motion and realize two-qubit gates. We characterized the implemented motion sensitive and insensitive single qubit processes and achieved a maximal process infidelity of 6 . 5 x 10 [?] 5 . We implemented the two-qubit gate proposed by Molmer and Sorensen and achieved a fidelity of more than 97 . 7%.
Plasmonic trace sensing below the photon shot noise limit
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Pooser, Raphael C.; Lawrie, Benjamin J.
2015-12-09
Plasmonic sensors are important detectors of biochemical trace compounds, but those that utilize optical readout are approaching their absolute limits of detection as defined by the Heisenberg uncertainty principle in both differential intensity and phase readout. However, the use of more general minimum uncertainty states in the form of squeezed light can push the noise floor in these sensors below the shot noise limit (SNL) in one analysis variable at the expense of another. Here, we demonstrate a quantum plasmonic sensor whose noise floor is reduced below the SNL in order to perform index of refraction measurements with sensitivities unobtainablemoreÂ Â» with classical plasmonic sensors. The increased signal-to-noise ratio can result in faster detection of analyte concentrations that were previously lost in the noise. As a result, these benefits are the hallmarks of a sensor exploiting quantum readout fields in order to manipulate the limits of the Heisenberg uncertainty principle.Â«Â less
Harsij, Zeynab Mirza, Behrouz
2014-12-15
A helicity entangled tripartite state is considered in which the degree of entanglement is preserved in non-inertial frames. It is shown that Quantum Entanglement remains observer independent. As another measure of quantum correlation, Quantum Discord has been investigated. It is explicitly shown that acceleration has no effect on the degree of quantum correlation for the bipartite and tripartite helicity entangled states. Geometric Quantum Discord as a Hilbert–Schmidt distance is computed for helicity entangled states. It is shown that living in non-inertial frames does not make any influence on this distance, either. In addition, the analysis has been extended beyond single mode approximation to show that acceleration does not have any impact on the quantum features in the limit beyond the single mode. As an interesting result, while the density matrix depends on the right and left Unruh modes, the Negativity as a measure of Quantum Entanglement remains constant. Also, Quantum Discord does not change beyond single mode approximation. - Highlights: • The helicity entangled states here are observer independent in non-inertial frames. • It is explicitly shown that Quantum Discord for these states is observer independent. • Geometric Quantum Discord is also not affected by acceleration increase. • Extending to beyond single mode does not change the degree of entanglement. • Beyond single mode approximation the degree of Quantum Discord is also preserved.
Quantum Solar | Open Energy Information
Solar Jump to: navigation, search Name: Quantum Solar Place: Santa Fe, New Mexico Zip: 87507 Product: New Mexico-based PV cell technology company. References: Quantum Solar1 This...
Quasiperiodically kicked quantum systems
Milonni, P.W.; Ackerhalt, J.R.; Goggin, M.E.
1987-02-15
We consider a two-state system kicked quasiperiodically by an external force. When the two kicking frequencies assumed for the force are incommensurate, there can be quantum chaos in the sense that (a) the autocorrelation function of the state vector decays, (b) the power spectrum of the state vector is broadband, and (c) the motion on the Bloch sphere is ergodic. The time evolution of the state vector is nevertheless dynamically stable in the sense that memory of the initial state is retained. We also consider briefly the kicked quantum rotator and find, in agreement with Shepelyansky (Physica 8D, 208 (1983)), that the quantum localization effect is greatly weakened by the presence of two incommensurate driving frequencies.
Efetov, K.B. [Max-Planck Institut fuer Physik komplexer Systeme, Heisenbergstrasse 1, 70569 Stuttgart (Germany)] [Max-Planck Institut fuer Physik komplexer Systeme, Heisenbergstrasse 1, 70569 Stuttgart (Germany); [L.D. Landau Institute for Theoretical Physics, Moscow (Russia)
1997-07-01
Quantum disordered problems with a direction (imaginary vector potential) are discussed and mapped onto a supermatrix {sigma} model. It is argued that the 0D version of the {sigma} model may describe a broad class of phenomena that can be called directed quantum chaos. It is demonstrated by explicit calculations that these problems are equivalent to those of random asymmetric or non-Hermitian matrices. A joint probability of complex eigenvalues is obtained. The fraction of states with real eigenvalues proves to be always finite for time reversal invariant systems. {copyright} {ital 1997} {ital The American Physical Society}
Quantum Statistical Testing of a Quantum Random Number Generator
Humble, Travis S
2014-01-01
The unobservable elements in a quantum technology, e.g., the quantum state, complicate system verification against promised behavior. Using model-based system engineering, we present methods for verifying the opera- tion of a prototypical quantum random number generator. We begin with the algorithmic design of the QRNG followed by the synthesis of its physical design requirements. We next discuss how quantum statistical testing can be used to verify device behavior as well as detect device bias. We conclude by highlighting how system design and verification methods must influence effort to certify future quantum technologies.
Comparison of the attempts of quantum discord and quantum entanglement to
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capture quantum correlations (Journal Article) | SciTech Connect Comparison of the attempts of quantum discord and quantum entanglement to capture quantum correlations Citation Details In-Document Search Title: Comparison of the attempts of quantum discord and quantum entanglement to capture quantum correlations Measurements of quantum systems disturb their states. To quantify this nonclassical characteristic, Zurek and Ollivier [Phys. Rev. Lett. 88, 017901 (2001)] introduced the quantum
Significant Quantum Effects in Hydrogen Activation
Kyriakou, Georgios; Davidson, Erlend R.; Peng, Guowen; Roling, Luke T.; Singh, Suyash; Boucher, Matthew B.; Marcinkowski, Matthew D.; Mavrikakis, Manos; Michaelides, Angelos; Sykes, E. Charles H.
2014-05-27
Dissociation of molecular hydrogen is an important step in a wide variety of chemical, biological, and physical processes. Due to the light mass of hydrogen, it is recognized that quantum effects are often important to its reactivity. However, understanding how quantum effects impact the reactivity of hydrogen is still in its infancy. Here, we examine this issue using a well-defined Pd/Cu(111) alloy that allows the activation of hydrogen and deuterium molecules to be examined at individual Pd atom surface sites over a wide range of temperatures. Experiments comparing the uptake of hydrogen and deuterium as a function of temperature reveal completely different behavior of the two species. The rate of hydrogen activation increases at lower sample temperature, whereas deuterium activation slows as the temperature is lowered. Density functional theory simulations in which quantum nuclear effects are accounted for reveal that tunneling through the dissociation barrier is prevalent for H2 up to 190 K and for D2 up to 140 K. Kinetic Monte Carlo simulations indicate that the effective barrier to H2 dissociation is so low that hydrogen uptake on the surface is limited merely by thermodynamics, whereas the D2 dissociation process is controlled by kinetics. These data illustrate the complexity and inherent quantum nature of this ubiquitous and seemingly simple chemical process. Examining these effects in other systems with a similar range of approaches may uncover temperature regimes where quantum effects can be harnessed, yielding greater control of bond-breaking processes at surfaces and uncovering useful chemistries such as selective bond activation or isotope separation.
The Quantum Energy Density: Improved E
Krogel, Jaron; Yu, Min; Kim, Jeongnim; Ceperley, David M.
2013-01-01
We establish a physically meaningful representation of a quantum energy density for use in Quantum Monte Carlo calculations. The energy density operator, dened in terms of Hamiltonian components and density operators, returns the correct Hamiltonian when integrated over a volume containing a cluster of particles. This property is demonstrated for a helium-neon \\gas," showing that atomic energies obtained from the energy density correspond to eigenvalues of isolated systems. The formation energies of defects or interfaces are typically calculated as total energy dierences. Using a model of delta-doped silicon (where dopant atoms form a thin plane) we show how interfacial energies can be calculated more eciently with the energy density, since the region of interest is small. We also demonstrate how the energy density correctly transitions to the bulk limit away from the interface where the correct energy is obtainable from a separate total energy calculation.
Quantum gravity effects in the Kerr spacetime
Reuter, M.; Tuiran, E.
2011-02-15
We analyze the impact of the leading quantum gravity effects on the properties of black holes with nonzero angular momentum by performing a suitable renormalization group improvement of the classical Kerr metric within quantum Einstein gravity. In particular, we explore the structure of the horizons, the ergosphere, and the static limit surfaces as well as the phase space available for the Penrose process. The positivity properties of the effective vacuum energy-momentum tensor are also discussed and the 'dressing' of the black hole's mass and angular momentum are investigated by computing the corresponding Komar integrals. The pertinent Smarr formula turns out to retain its classical form. As for their thermodynamical properties, a modified first law of black-hole thermodynamics is found to be satisfied by the improved black holes (to second order in the angular momentum); the corresponding Bekenstein-Hawking temperature is not proportional to the surface gravity.
Comparison of quantum confinement effects between quantum wires and dots
Li, Jingbo; Wang, Lin-Wang
2004-03-30
Dimensionality is an important factor to govern the electronic structures of semiconductor nanocrystals. The quantum confinement energies in one-dimensional quantum wires and zero-dimensional quantum dots are quite different. Using large-scale first-principles calculations, we systematically study the electronic structures of semiconductor (including group IV, III-V, and II-VI) surface-passivated quantum wires and dots. The band-gap energies of quantum wires and dots have the same scaling with diameter for a given material. The ratio of band-gap-increases between quantum wires and dots is material-dependent, and slightly deviates from 0.586 predicted by effective-mass approximation. Highly linear polarization of photoluminescence in quantum wires is found. The degree of polarization decreases with the increasing temperature and size.
Reducing collective quantum state rotation errors with reversible dephasing
Cox, Kevin C.; Norcia, Matthew A.; Weiner, Joshua M.; Bohnet, Justin G.; Thompson, James K.
2014-12-29
We demonstrate that reversible dephasing via inhomogeneous broadening can greatly reduce collective quantum state rotation errors, and observe the suppression of rotation errors by more than 21?dB in the context of collective population measurements of the spin states of an ensemble of 2.1×10{sup 5} laser cooled and trapped {sup 87}Rb atoms. The large reduction in rotation noise enables direct resolution of spin state populations 13(1) dB below the fundamental quantum projection noise limit. Further, the spin state measurement projects the system into an entangled state with 9.5(5) dB of directly observed spectroscopic enhancement (squeezing) relative to the standard quantum limit, whereas no enhancement would have been obtained without the suppression of rotation errors.
Classical and quantum chaos in atomic systems
Delande, D.; Buchleitner, A. [Universite Pierre et Marie Curie, Paris (France)
1994-12-31
Atomic systems played a major role in the birth and growth of quantum mechanics. One central idea was to relate the well-known classical motion of the electron of a hydrogen atom--an ellipsis around the nucleus--to the experimentally observed quantization of the energy levels. This is the aim of the Bohr and Bohr-Sommerfeld models. These simple semiclassical models were unable to make any reliable prediction on the energy spectrum of the next simplest atom, helium. Because of the great success of quantum mechanics, the problem of correspondence between the classical and the quantal dynamics has not received much attention in the last 60 years. The fundamental question is (Gutzwiller, 1990). How can classical mechanics be understood as a limiting case within quantum mechanics? For systems with time-independent one-dimensional dynamics like the harmonic oscillator and the hydrogen atom, the correspondence is well understood. The restriction to such simple cases creates the erroneous impression that the classical behavior of simple systems is entirely comprehensible and easily described. During the last 20 years it has been recognized that this in not true and that a complex behavior can be obtained from simple equations of motion. This usually happens when the motion is chaotic, that is, unpredictable on a long time scale although perfectly deterministic (Henon, 1983). A major problem is that of understanding how the regular or chaotic behavior of the classical system is manifest in its quantum properties, especially in the semiclassical limit. 53 refs., 15 figs., 1 tab.
McBranch, D.W.; Mattes, B.R.; Koskelo, A.C.; Heeger, A.J.; Robinson, J.M.; Smilowitz, L.B.; Klimov, V.I.; Cha, M.; Sariciftci, N.S.; Hummelen, J.C.
1998-04-21
Methanofullerenes, fulleroids and/or other fullerenes chemically altered for enhanced solubility, in liquid solution, and in solid blends with transparent glass (SiO{sub 2}) gels or polymers, or semiconducting (conjugated) polymers, are shown to be useful as optical limiters (optical surge protectors). The nonlinear absorption is tunable such that the energy transmitted through such blends saturates at high input energy per pulse over a wide range of wavelengths from 400--1,100 nm by selecting the host material for its absorption wavelength and ability to transfer the absorbed energy into the optical limiting composition dissolved therein. This phenomenon should be generalizable to other compositions than substituted fullerenes. 5 figs.
Security Clearances; Limitations
SEC. 1072. SECURITY CLEARANCES; LIMITATIONS. (a) In General.-Title III of the Intelligence Reform and Terrorism Prevention Act of 2004 (50 U.S.C. 435b) is amended by adding at the end the following new section: "SEC. 3002. SECURITY CLEARANCES; LIMITATIONS. "(a) Definitions.-In this section: "(1) Controlled substance.-The term `controlled substance' has the meaning given that term in section 102 of the Controlled Substances Act (21 U.S.C. 802). "(2) Covered person.-The term
Nanowire terahertz quantum cascade lasers
Grange, Thomas
2014-10-06
Quantum cascade lasers made of nanowire axial heterostructures are proposed. The dissipative quantum dynamics of their carriers is theoretically investigated using non-equilibrium Green functions. Their transport and gain properties are calculated for varying nanowire thickness, from the classical-wire regime to the quantum-wire regime. Our calculation shows that the lateral quantum confinement provided by the nanowires allows an increase of the maximum operation temperature and a strong reduction of the current density threshold compared to conventional terahertz quantum cascade lasers.
Deformation Quantization: Quantum Mechanic Lives and Works in...
Office of Scientific and Technical Information (OSTI)
of the density matrix. It has been useful in describing quantum flows in: quantum optics; nuclear physics; decoherence (eg, quantum computing); quantum chaos; 'Welcher Weg'...
Harris, William G. (Tampa, FL)
1985-01-01
A heat limiting tubular sleeve extending over only a portion of a tube having a generally uniform outside diameter, the sleeve being open on both ends, having one end thereof larger in diameter than the other end thereof and having a wall thickness which decreases in the same direction as the diameter of the sleeve decreases so that the heat transfer through the sleeve and tube is less adjacent the large diameter end of the sleeve than adjacent the other end thereof.
Office of Environmental Management (EM)
Fault Current Limiters Superconducting & Solid-state Power Equipment Office of Electricity Delivery and Energy Reliability www.oe.energy.gov Office of Electricity Delivery and Energy Reliability, OE-1 U.S. Department of Energy - 1000 Independence Avenue, SW - Washington, DC 20585 Plugging America Into the Future of Power What are FCLs? A fault is an unintentional short circuit, or partial short-circuit, in an electric circuit. A variety of factors such as lightning, downed power lines, or
Deterministic generation of remote entanglement with active quantum feedback
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Martin, Leigh; Motzoi, Felix; Li, Hanhan; Sarovar, Mohan; Whaley, K. Birgitta
2015-12-10
We develop and study protocols for deterministic remote entanglement generation using quantum feedback, without relying on an entangling Hamiltonian. In order to formulate the most effective experimentally feasible protocol, we introduce the notion of average-sense locally optimal feedback protocols, which do not require real-time quantum state estimation, a difficult component of real-time quantum feedback control. We use this notion of optimality to construct two protocols that can deterministically create maximal entanglement: a semiclassical feedback protocol for low-efficiency measurements and a quantum feedback protocol for high-efficiency measurements. The latter reduces to direct feedback in the continuous-time limit, whose dynamics can bemoreÂ Â» modeled by a Wiseman-Milburn feedback master equation, which yields an analytic solution in the limit of unit measurement efficiency. Our formalism can smoothly interpolate between continuous-time and discrete-time descriptions of feedback dynamics and we exploit this feature to derive a superior hybrid protocol for arbitrary nonunit measurement efficiency that switches between quantum and semiclassical protocols. Lastly, we show using simulations incorporating experimental imperfections that deterministic entanglement of remote superconducting qubits may be achieved with current technology using the continuous-time feedback protocol alone.Â«Â less
Deterministic generation of remote entanglement with active quantum feedback
Martin, Leigh; Motzoi, Felix; Li, Hanhan; Sarovar, Mohan; Whaley, K. Birgitta
2015-12-10
We develop and study protocols for deterministic remote entanglement generation using quantum feedback, without relying on an entangling Hamiltonian. In order to formulate the most effective experimentally feasible protocol, we introduce the notion of average-sense locally optimal feedback protocols, which do not require real-time quantum state estimation, a difficult component of real-time quantum feedback control. We use this notion of optimality to construct two protocols that can deterministically create maximal entanglement: a semiclassical feedback protocol for low-efficiency measurements and a quantum feedback protocol for high-efficiency measurements. The latter reduces to direct feedback in the continuous-time limit, whose dynamics can be modeled by a Wiseman-Milburn feedback master equation, which yields an analytic solution in the limit of unit measurement efficiency. Our formalism can smoothly interpolate between continuous-time and discrete-time descriptions of feedback dynamics and we exploit this feature to derive a superior hybrid protocol for arbitrary nonunit measurement efficiency that switches between quantum and semiclassical protocols. Lastly, we show using simulations incorporating experimental imperfections that deterministic entanglement of remote superconducting qubits may be achieved with current technology using the continuous-time feedback protocol alone.
'Giant' Nanocrystal Quantum Dots
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'Giant' Nanocrystal Quantum Dots - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Fuel Cycle Defense Waste Management Programs
A tamper-indicating quantum seal
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Williams, Brian P.; Britt, Keith A.; Humble, Travis S.
2016-01-04
Technical means for identifying when tampering occurs is a critical part of many containment and surveillance technologies. Conventional fiber optic seals provide methods for monitoring enclosed inventories, but they are vulnerable to spoofing attacks based on classical physics. We address these vulnerabilities with the development of a quantum seal that offers the ability to detect the intercept-resend attack using quantum integrity verification. Our approach represents an application of entanglement to provide guarantees in the authenticity of the seal state by verifying it was transmitted coherently. We implement these ideas using polarization-entangled photon pairs that are verified after passing through amoreÂ Â» fiber-optic channel testbed. Using binary detection theory, we find the probability of detecting inauthentic signals is greater than 0.9999 with a false alarm chance of 10â€“9 for a 10 second sampling interval. In addition, we show how the Hong-Ou-Mandel effect concurrently provides a tight bound on redirection attack, in which tampering modifies the shape of the seal. Our measurements limit the tolerable path length change to sub-millimeter disturbances. As a result, these tamper-indicating features of the quantum seal offer unprecedented security for unattended monitoring systems.Â«Â less
Quantum Computing: Solving Complex Problems
DiVincenzo, David [IBM Watson Research Center
2009-09-01
One of the motivating ideas of quantum computation was that there could be a new kind of machine that would solve hard problems in quantum mechanics. There has been significant progress towards the experimental realization of these machines (which I will review), but there are still many questions about how such a machine could solve computational problems of interest in quantum physics. New categorizations of the complexity of computational problems have now been invented to describe quantum simulation. The bad news is that some of these problems are believed to be intractable even on a quantum computer, falling into a quantum analog of the NP class. The good news is that there are many other new classifications of tractability that may apply to several situations of physical interest.
Spatially indirect excitons in coupled quantum wells
Lai, Chih-Wei Eddy
2004-03-01
Microscopic quantum phenomena such as interference or phase coherence between different quantum states are rarely manifest in macroscopic systems due to a lack of significant correlation between different states. An exciton system is one candidate for observation of possible quantum collective effects. In the dilute limit, excitons in semiconductors behave as bosons and are expected to undergo Bose-Einstein condensation (BEC) at a temperature several orders of magnitude higher than for atomic BEC because of their light mass. Furthermore, well-developed modern semiconductor technologies offer flexible manipulations of an exciton system. Realization of BEC in solid-state systems can thus provide new opportunities for macroscopic quantum coherence research. In semiconductor coupled quantum wells (CQW) under across-well static electric field, excitons exist as separately confined electron-hole pairs. These spatially indirect excitons exhibit a radiative recombination time much longer than their thermal relaxation time a unique feature in direct band gap semiconductor based structures. Their mutual repulsive dipole interaction further stabilizes the exciton system at low temperature and screens in-plane disorder more effectively. All these features make indirect excitons in CQW a promising system to search for quantum collective effects. Properties of indirect excitons in CQW have been analyzed and investigated extensively. The experimental results based on time-integrated or time-resolved spatially-resolved photoluminescence (PL) spectroscopy and imaging are reported in two categories. (i) Generic indirect exciton systems: general properties of indirect excitons such as the dependence of exciton energy and lifetime on electric fields and densities were examined. (ii) Quasi-two-dimensional confined exciton systems: highly statistically degenerate exciton systems containing more than tens of thousands of excitons within areas as small as (10 micrometer){sup 2} were observed. The spatial and energy distributions of optically active excitons were used as thermodynamic quantities to construct a phase diagram of the exciton system, demonstrating the existence of distinct phases. Optical and electrical properties of the CQW sample were examined thoroughly to provide deeper understanding of the formation mechanisms of these cold exciton systems. These insights offer new strategies for producing cold exciton systems, which may lead to opportunities for the realization of BEC in solid-state systems.
Darmann, Francis Anthony
2013-10-08
A fault current limiter (FCL) includes a series of high permeability posts for collectively define a core for the FCL. A DC coil, for the purposes of saturating a portion of the high permeability posts, surrounds the complete structure outside of an enclosure in the form of a vessel. The vessel contains a dielectric insulation medium. AC coils, for transporting AC current, are wound on insulating formers and electrically interconnected to each other in a manner such that the senses of the magnetic field produced by each AC coil in the corresponding high permeability core are opposing. There are insulation barriers between phases to improve dielectric withstand properties of the dielectric medium.
Quantum chaos and fluctuations in isolated nuclear-spin systems
Ludlow, J. A.; Sushkov, O. P. [School of Physics, University of New South Wales, Sydney 2052 (Australia)
2007-01-15
Using numerical simulations we investigate dynamical quantum chaos in isolated nuclear spin systems. We determine the structure of quantum states, investigate the validity of the Curie law for magnetic susceptibility and find the spectrum of magnetic noise. The spectrum is the same for positive and negative temperatures. The study is motivated by recent interest in condensed-matter experiments for searches of fundamental parity- and time-reversal-invariance violations. In these experiments nuclear spins are cooled down to microkelvin temperatures and are completely decoupled from their surroundings. A limitation on statistical sensitivity of the experiments arises from the magnetic noise.
Quantum rings of non-uniform thickness in magnetic field
Rodríguez-Prada, F. A.; García, L. F.; Mikhailov, I. D.
2014-05-15
We consider a model of crater-shaped quantum dot in form of a thin layer whose thickness linearly increases with the distance from the axis. We show that one-particle wave equation for the electron confined in such structure can be completely separated in the adiabatic limit when the quantum dot thickness is much smaller than its lateral dimension. Analytical solutions found for this model has been used as base functions for analysing the effect of non-homogeneity on the electronic spectrum in the framework of the exact diagonalization method.
(Limiting the greenhouse effect)
Rayner, S.
1991-01-07
Traveler attended the Dahlem Research Conference organized by the Freien Universitat, Berlin. The subject of the conference was Limiting the Greenhouse Effect: Options for Controlling Atmospheric CO{sub 2} Accumulation. Like all Dahlem workshops, this was a meeting of scientific experts, although the disciplines represented were broader than usual, ranging across anthropology, economics, international relations, forestry, engineering, and atmospheric chemistry. Participation by scientists from developing countries was limited. The conference was divided into four multidisciplinary working groups. Traveler acted as moderator for Group 3 which examined the question What knowledge is required to tackle the principal social and institutional barriers to reducing CO{sub 2} emissions'' The working rapporteur was Jesse Ausubel of Rockefeller University. Other working groups examined the economic costs, benefits, and technical feasibility of options to reduce emissions per unit of energy service; the options for reducing energy use per unit of GNP; and the significant of linkage between strategies to reduce CO{sub 2} emissions and other goals. Draft reports of the working groups are appended. Overall, the conference identified a number of important research needs in all four areas. It may prove particularly important in bringing the social and institutional research needs relevant to climate change closer to the forefront of the scientific and policy communities than hitherto.
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Outsmarting Thermodynamics in Self-assembly of Nanostructures If you can uniformly break the symmetry of nanorod pairs in a colloidal solution, you're one step closer to achieving new and exciting metamaterial properties. The development of an innovative self-assembly route could surpass the conventional thermodynamic limit in chemical synthetic systems and lead to the production of nanostructures that have historically been considered impossible to assemble. But traditional thermodynamic-driven
Quantum error-correcting codes and devices
Gottesman, Daniel (Los Alamos, NM)
2000-10-03
A method of forming quantum error-correcting codes by first forming a stabilizer for a Hilbert space. A quantum information processing device can be formed to implement such quantum codes.
Quantum chaos for exact and broken K quantum number in the interacting-boson model
Paar, V.; Vorkapic, D. (Prirodoslovno-matematicki fakultet, University of Zagreb, 41000 Zagreb, Yugoslavia (YU))
1990-05-01
We show that the exact {ital K} quantum number in the SU(3) limit of the interacting-boson model has a strong effect on the fluctuation properties: Pure sequences of a single {ital K} value have {Delta}{sub 3} statistic close to the Gaussian overlap ensemble prediction while mixed sequences with combined {ital K} values are removed far from the Gaussian overlap ensemble because of {ital K} degeneracy, exceeding even the Poisson-ensemble prediction. Applying the extended interacting boson model to the realistic case of {sup 164}Er nucleus, we have demonstrated that weak breaking of the {ital K} quantum number introduces a very rapid change in fluctuation properties towards those of a pure sequence.
Timminco Limited | Open Energy Information
Limited Jump to: navigation, search Name: Timminco Limited Place: Toronto, Ontario, Canada Zip: M5H 1J9 Product: Canadian manufacturer of magnesium and silicon; operates its...
Quantum Enabled Security (QES) for Optical Communications
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Laboratory has developed Quantum Enabled Security (QES), a revolutionary new cybersecurity capability using quantum (single-photon) communications integrated with optical...
Nuclear Scission and Quantum Localization (Journal Article) ...
Office of Scientific and Technical Information (OSTI)
Journal Article: Nuclear Scission and Quantum Localization Citation Details In-Document Search Title: Nuclear Scission and Quantum Localization You are accessing a document from...
QuantumSphere Inc | Open Energy Information
QuantumSphere Inc Jump to: navigation, search Name: QuantumSphere Inc Place: Santa Ana, California Zip: Santa Ana, CA 92705 Product: Manufacturer of metallic nanopowders for...
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing...
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Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Wednesday, 26 August 2009 00:00 Rotaxanes are...
Applied Quantum Technology AQT | Open Energy Information
Quantum Technology AQT Jump to: navigation, search Name: Applied Quantum Technology (AQT) Place: Santa Clara, California Zip: 95054 Product: California-based manufacturer of CIGS...
Infrared microcalorimetric spectroscopy using quantum cascade...
Office of Scientific and Technical Information (OSTI)
Infrared microcalorimetric spectroscopy using quantum cascade lasers Citation Details In-Document Search Title: Infrared microcalorimetric spectroscopy using quantum cascade lasers...
Quantum simulation of quantum field theory using continuous variables
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Marshall, Kevin; Pooser, Raphael C.; Siopsis, George; Weedbrook, Christian
2015-12-14
Much progress has been made in the field of quantum computing using continuous variables over the last couple of years. This includes the generation of extremely large entangled cluster states (10,000 modes, in fact) as well as a fault tolerant architecture. This has lead to the point that continuous-variable quantum computing can indeed be thought of as a viable alternative for universal quantum computing. With that in mind, we present a new algorithm for continuous-variable quantum computers which gives an exponential speedup over the best known classical methods. Specifically, this relates to efficiently calculating the scattering amplitudes in scalar bosonicmoreÂ Â» quantum field theory, a problem that is known to be hard using a classical computer. Thus, we give an experimental implementation based on cluster states that is feasible with today's technology.Â«Â less
Quantum interference within the complex quantum Hamilton-Jacobi formalism
Chou, Chia-Chun; Sanz, Angel S.; Miret-Artes, Salvador; Wyatt, Robert E.
2010-10-15
Quantum interference is investigated within the complex quantum Hamilton-Jacobi formalism. As shown in a previous work [Phys. Rev. Lett. 102 (2009) 250401], complex quantum trajectories display helical wrapping around stagnation tubes and hyperbolic deflection near vortical tubes, these structures being prominent features of quantum caves in space-time Argand plots. Here, we further analyze the divergence and vorticity of the quantum momentum function along streamlines near poles, showing the intricacy of the complex dynamics. Nevertheless, despite this behavior, we show that the appearance of the well-known interference features (on the real axis) can be easily understood in terms of the rotation of the nodal line in the complex plane. This offers a unified description of interference as well as an elegant and practical method to compute the lifetime for interference features, defined in terms of the average wrapping time, i.e., considering such features as a resonant process.
Quantum emitters dynamically coupled to a quantum field
Acevedo, O. L.; Quiroga, L.; Rodríguez, F. J.; Johnson, N. F.
2013-12-04
We study theoretically the dynamical response of a set of solid-state quantum emitters arbitrarily coupled to a single-mode microcavity system. Ramping the matter-field coupling strength in round trips, we quantify the hysteresis or irreversible quantum dynamics. The matter-field system is modeled as a finite-size Dicke model which has previously been used to describe equilibrium (including quantum phase transition) properties of systems such as quantum dots in a microcavity. Here we extend this model to address non-equilibrium situations. Analyzing the system’s quantum fidelity, we find that the near-adiabatic regime exhibits the richest phenomena, with a strong asymmetry in the internal collective dynamics depending on which phase is chosen as the starting point. We also explore signatures of the crossing of the critical points on the radiation subsystem by monitoring its Wigner function; then, the subsystem can exhibit the emergence of non-classicality and complexity.
Quantum Darwinism, Decoherence, and the Randomness of Quantum Jumps
Zurek, Wojciech H.
2014-06-05
Tracing flows of information in our quantum Universe explains why we see the world as classical. Quantum principle of superposition decrees every combination of quantum states a legal quantum state. This is at odds with our experience. Decoherence selects preferred pointer states that survive interaction with the environment. They are localized and effectively classical. They persist while their superpositions decohere. Here we consider emergence of `the classical' starting at a more fundamental pre-decoherence level, tracing the origin of preferred pointer states and deducing their probabilities from the core quantum postulates. We also explore role of the environment as medium through which observers acquire information. This mode of information transfer leads to perception of objective classical reality.
Transport signatures of quantum critically in Cr at high pressure.
Jaramillo, R.; Feng, Y.; Wang, J.; Rosenbaum, T. F.
2010-08-03
The elemental antiferromagnet Cr at high pressure presents a new type of naked quantum critical point that is free of disorder and symmetry-breaking fields. Here we measure magnetotransport in fine detail around the critical pressure, P{sub c} {approx} 10 GPa, in a diamond anvil cell and reveal the role of quantum critical fluctuations at the phase transition. As the magnetism disappears and T {yields} 0, the magntotransport scaling converges to a non-mean-field form that illustrates the reconstruction of the magnetic Fermi surface, and is distinct from the critical scaling measured in chemically disordered Cr:V under pressure. The breakdown of itinerant antiferromagnetism only comes clearly into view in the clean limit, establishing disorder as a relevant variable at a quantum phase transition.
Quantum Dot Solar Cells with Multiple Exciton Generation
Hanna, M. C.; Beard, M. C.; Johnson, J. C.; Murphy, J.; Ellingson, R. J.; Nozik, A. J.
2005-11-01
We have measured the quantum yield of the multiple exciton generation (MEG) process in quantum dots (QDs) of the lead-salt semiconductor family (PbSe, PbTe, and PbS) using fs pump-probe transient absorption measurements. Very high quantum yields (up to 300%) for charge carrier generation from MEG have been measured in all of the Pb-VI QDs. We have calculated the potential maximum performance of various MEG QD solar cells in the detailed balance limit. We examined a two-cell tandem PV device with singlet fission (SF), QD, and normal dye (N) absorbers in the nine possible series-connected combinations to compare the tandem combinations and identify the combinations with the highest theoretical efficiency. We also calculated the maximum efficiency of an idealized single-gap MEG QD solar cell with M multiplications and its performance under solar concentration.
Quantum gravity slows inflation
Tsamis, N.C. |; Woodard, R.P.
1996-02-01
We consider the quantum gravitational back-reaction on an initially inflating, homogeneous and isotropic universe whose topology is T{sup 3} {times} {Re}. Although there is no secular effect at one loop, an explicit calculation shows that two-loop processes act to slow the rate of expansion by an amount which becomes non-pertubatively large at late times. By exploiting Feynman`s tree theorem we show that all higher loops act in the same sense. 18 refs., 1 fig.
QUANTUM MECHANICS WITHOUT STATISTICAL POSTULATES
G. GEIGER; ET AL
2000-11-01
The Bohmian formulation of quantum mechanics describes the measurement process in an intuitive way without a reduction postulate. Due to the chaotic motion of the hidden classical particle all statistical features of quantum mechanics during a sequence of repeated measurements can be derived in the framework of a deterministic single system theory.
PERTURBATION APPROACH FOR QUANTUM COMPUTATION
G. P. BERMAN; D. I. KAMENEV; V. I. TSIFRINOVICH
2001-04-01
We discuss how to simulate errors in the implementation of simple quantum logic operations in a nuclear spin quantum computer with many qubits, using radio-frequency pulses. We verify our perturbation approach using the exact solutions for relatively small (L = 10) number of qubits.
Interface effect in coupled quantum wells
Hao, Ya-Fei
2014-06-28
This paper intends to theoretically investigate the effect of the interfaces on the Rashba spin splitting of two coupled quantum wells. The results show that the interface related Rashba spin splitting of the two coupled quantum wells is both smaller than that of a step quantum well which has the same structure with the step quantum well in the coupled quantum wells. And the influence of the cubic Dresselhaus spin-orbit interaction of the coupled quantum wells is larger than that of a step quantum well. It demonstrates that the spin relaxation time of the two coupled quantum wells will be shorter than that of a step quantum well. As for the application in the spintronic devices, a step quantum well may be better than the coupled quantum wells, which is mentioned in this paper.
Quantum Criticality and Black Holes
Sachdev, Subir [Harvard University, Cambridge, Massachusetts, United States
2009-09-01
I will describe the behavior of a variety of condensed matter systems in the vicinity of zero temperature quantum phase transitions. There is a remarkable analogy between the hydrodynamics of such systems and the quantum theory of black holes. I will show how insights from this analogy have shed light on recent experiments on the cuprate high temperature superconductors. Studies of new materials and trapped ultracold atoms are yielding new quantum phases, with novel forms of quantum entanglement. Some materials are of technological importance: e.g. high temperature superconductors. Exact solutions via black hole mapping have yielded first exact results for transport coefficients in interacting many-body systems, and were valuable in determining general structure of hydrodynamics. Theory of VBS order and Nernst effect in cuprates. Tabletop 'laboratories for the entire universe': quantum mechanics of black holes, quark-gluon plasma, neutrons stars, and big-bang physics.
Deformation quantization : quantum mechanics lives and works in phase-space.
Zachos, C.; High Energy Physics
2002-01-30
Wigner's quasi-probability distribution function in phase-space is a special (Weyl) representation of the density matrix. It has been useful in describing quantum transport in quantum optics; nuclear physics; decoherence (e.g. quantum computing); quantum chaos; 'Welcher Weg' discussions; semiclassical limits. It is also of importance in signal processing. Nevertheless, a remarkable aspect of its internal logic, pioneered by Moyal, has only emerged in the last quarter-century: It furnishes a third, alternative, formulation of Quantum Mechanics, independent of the conventional Hilbert Space, or Path Integral formulations. In this logically complete and self-standing formulation, one need not choose sides--coordinate or momentum space. It works in full phase-space, accommodating the uncertainty principle. This is an introductory overview of the formulation with simple illustrations.
Deformation Quantization: Quantum Mechanic Lives and Works in Phase-Space
Zachos, Cosmas (Argonne National Laboratory) [Argonne National Laboratory
2001-08-01
Wigner's 1932 quasi-probability Distribution Function in phase-space is a special (Weyl) representation of the density matrix. It has been useful in describing quantum flows in: quantum optics; nuclear physics; decoherence (eg, quantum computing); quantum chaos; 'Welcher Weg' discussions; semiclassical limits. It is also of importance in signal processing. Nevertheless, a remarkable aspect of its internal logic, pioneered by the late Moyal, has only emerged in the last quarter-century: It furnishes a third, alternate, formulation of Quantum Mechanics, independent of the conventional Hilbert Space, or Path Integral formulations. It is logically complete and self-standing, and accommodates the uncertainty principle in an unexpected manner. Simple illustrations of this fact will be detailed.
Quantum interference in polyenes
Tsuji, Yuta; Hoffmann, Roald; Movassagh, Ramis; Datta, Supriyo
2014-12-14
The explicit form of the zeroth Green's function in the Hückel model, approximated by the negative of the inverse of the Hückel matrix, has direct quantum interference consequences for molecular conductance. We derive a set of rules for transmission between two electrodes attached to a polyene, when the molecule is extended by an even number of carbons at either end (transmission unchanged) or by an odd number of carbons at both ends (transmission turned on or annihilated). These prescriptions for the occurrence of quantum interference lead to an unexpected consequence for switches which realize such extension through electrocyclic reactions: for some specific attachment modes the chemically closed ring will be the ON position of the switch. Normally the signs of the entries of the Green's function matrix are assumed to have no physical significance; however, we show that the signs may have observable consequences. In particular, in the case of multiple probe attachments – if coherence in probe connections can be arranged – in some cases new destructive interference results, while in others one may have constructive interference. One such case may already exist in the literature.
Universal quantum computation in a semiconductor quantum wire network
Sau, Jay D.; Das Sarma, S.; Tewari, Sumanta
2010-11-15
Universal quantum computation (UQC) using Majorana fermions on a two-dimensional topological superconducting (TS) medium remains an outstanding open problem. This is because the quantum gate set that can be generated by braiding of the Majorana fermions does not include any two-qubit gate and also no single-qubit {pi}/8 phase gate. In principle, it is possible to create these crucial extra gates using quantum interference of Majorana fermion currents. However, it is not clear if the motion of the various order parameter defects (vortices, domain walls, etc.), to which the Majorana fermions are bound in a TS medium, can be quantum coherent. We show that these obstacles can be overcome using a semiconductor quantum wire network in the vicinity of an s-wave superconductor, by constructing topologically protected two-qubit gates and any arbitrary single-qubit phase gate in a topologically unprotected manner, which can be error corrected using magic-state distillation. Thus our strategy, using a judicious combination of topologically protected and unprotected gate operations, realizes UQC on a quantum wire network with a remarkably high error threshold of 0.14 as compared to 10{sup -3} to 10{sup -4} in ordinary unprotected quantum computation.
Energy density matrix formalism for interacting quantum systems: a quantum Monte Carlo study
Krogel, Jaron T; Kim, Jeongnim; Reboredo, Fernando A
2014-01-01
We develop an energy density matrix that parallels the one-body reduced density matrix (1RDM) for many-body quantum systems. Just as the density matrix gives access to the number density and occupation numbers, the energy density matrix yields the energy density and orbital occupation energies. The eigenvectors of the matrix provide a natural orbital partitioning of the energy density while the eigenvalues comprise a single particle energy spectrum obeying a total energy sum rule. For mean-field systems the energy density matrix recovers the exact spectrum. When correlation becomes important, the occupation energies resemble quasiparticle energies in some respects. We explore the occupation energy spectrum for the finite 3D homogeneous electron gas in the metallic regime and an isolated oxygen atom with ground state quantum Monte Carlo techniques imple- mented in the QMCPACK simulation code. The occupation energy spectrum for the homogeneous electron gas can be described by an effective mass below the Fermi level. Above the Fermi level evanescent behavior in the occupation energies is observed in similar fashion to the occupation numbers of the 1RDM. A direct comparison with total energy differences demonstrates a quantita- tive connection between the occupation energies and electron addition and removal energies for the electron gas. For the oxygen atom, the association between the ground state occupation energies and particle addition and removal energies becomes only qualitative. The energy density matrix provides a new avenue for describing energetics with quantum Monte Carlo methods which have traditionally been limited to total energies.
Flavored quantum Boltzmann equations
Cirigliano, Vincenzo; Lee, Christopher; Ramsey-Musolf, Michael J.; Tulin, Sean [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545 (United States); Center for Theoretical Physics, University of California, and Theoretical Physics Group, Lawrence Berkeley National Laboratory, Berkeley, California, 94720 (United States); Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin, 53706 (United States) and Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California, 91125 (United States); Theory Group, TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3 (Canada)
2010-05-15
We derive from first principles, using nonequilibrium field theory, the quantum Boltzmann equations that describe the dynamics of flavor oscillations, collisions, and a time-dependent mass matrix in the early universe. Working to leading nontrivial order in ratios of relevant time scales, we study in detail a toy model for weak-scale baryogenesis: two scalar species that mix through a slowly varying time-dependent and CP-violating mass matrix, and interact with a thermal bath. This model clearly illustrates how the CP asymmetry arises through coherent flavor oscillations in a nontrivial background. We solve the Boltzmann equations numerically for the density matrices, investigating the impact of collisions in various regimes.
Phase space quantum mechanics - Direct
Nasiri, S.; Sobouti, Y.; Taati, F.
2006-09-15
Conventional approach to quantum mechanics in phase space (q,p), is to take the operator based quantum mechanics of Schroedinger, or an equivalent, and assign a c-number function in phase space to it. We propose to begin with a higher level of abstraction, in which the independence and the symmetric role of q and p is maintained throughout, and at once arrive at phase space state functions. Upon reduction to the q- or p-space the proposed formalism gives the conventional quantum mechanics, however, with a definite rule for ordering of factors of noncommuting observables. Further conceptual and practical merits of the formalism are demonstrated throughout the text.
Quantum Field Theory & Gravity
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Quantum Field Theory & Gravity Quantum Field Theory & Gravity Understanding discoveries at the Energy, Intensity, and Cosmic Frontiers Get Expertise Rajan Gupta (505) 667-7664 Email Bruce Carlsten (505) 667-5657 Email Quantum Field Theory and Gravity at Los Alamos The HEP effort at Los Alamos in this area is actively pursing a number of questions in this area. What is the final state of complete gravitational collapse? What happens at the event horizon? What is dark energy? How did the
COMMENTARY:Limits to adaptation
Preston, Benjamin L
2013-01-01
An actor-centered, risk-based approach to defining limits to social adaptation provides a useful analytic framing for identifying and anticipating these limits and informing debates over society s responses to climate change.
Smartphone data safety with quantum cryptography
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Smartphone data safety with quantum cryptography Smartphone data safety with quantum cryptography Laws of quantum physics and information theory ensure that smartphones with QKarD could never be compromised. January 20, 2012 The QKarD encodes security keys on a photon using quantum mechanical principles. The miniature transmitter communicates with a trusted authority to generate random cryptographic keys to encode and decode information. The QKarD encodes security keys on a photon using quantum
The fundamental downscaling limit of field effect transistors
Mamaluy, Denis Gao, Xujiao
2015-05-11
We predict that within next 15 years a fundamental down-scaling limit for CMOS technology and other Field-Effect Transistors (FETs) will be reached. Specifically, we show that at room temperatures all FETs, irrespective of their channel material, will start experiencing unacceptable level of thermally induced errors around 5-nm gate lengths. These findings were confirmed by performing quantum mechanical transport simulations for a variety of 6-, 5-, and 4-nm gate length Si devices, optimized to satisfy high-performance logic specifications by ITRS. Different channel materials and wafer/channel orientations have also been studied; it is found that altering channel-source-drain materials achieves only insignificant increase in switching energy, which overall cannot sufficiently delay the approaching downscaling limit. Alternative possibilities are discussed to continue the increase of logic element densities for room temperature operation below the said limit.
Scalable quantum computer architecture with coupled donor-quantum dot qubits
Schenkel, Thomas; Lo, Cheuk Chi; Weis, Christoph; Lyon, Stephen; Tyryshkin, Alexei; Bokor, Jeffrey
2014-08-26
A quantum bit computing architecture includes a plurality of single spin memory donor atoms embedded in a semiconductor layer, a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, wherein a first voltage applied across at least one pair of the aligned quantum dot and donor atom controls a donor-quantum dot coupling. A method of performing quantum computing in a scalable architecture quantum computing apparatus includes arranging a pattern of single spin memory donor atoms in a semiconductor layer, forming a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, applying a first voltage across at least one aligned pair of a quantum dot and donor atom to control a donor-quantum dot coupling, and applying a second voltage between one or more quantum dots to control a Heisenberg exchange J coupling between quantum dots and to cause transport of a single spin polarized electron between quantum dots.
Quantum fluctuations in beam dynamics.
Kim, K.-J.
1998-06-04
Quantum effects could become important for particle and photon beams used in high-luminosity and high brightness applications in the current and next generation accelerators and radiation sources. This paper is a review of some of these effects.
Santa Fe New Mexican: For cybersecurity, in quantum encryption...
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For cybersecurity, in quantum encryption we trust Santa Fe New Mexican: For cybersecurity, in quantum encryption we trust Los Alamos physicists developed a quantum random number...
Promising future of quantum dots explored in conference
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Promising future of quantum dots explored Promising future of quantum dots explored in conference Researchers are gathering to reflect on two decades of quantum dot research at a...
Nanoscale engineering boosts performance of quantum dot light...
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Quantum dot light emitting diodes Nanoscale engineering boosts performance of quantum dot light emitting diodes Quantum dots are nano-sized semiconductor particles whose emission...
The Quantum Way of Sensing | Argonne Leadership Computing Facility
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quantum optics and spintronics. He counts as a pioneer in the field of solid state spin quantum physics and has explored applications in photonics, spintronics, quantum computing ...
Convex polytopes and quantum separability
Holik, F.; Plastino, A.
2011-12-15
We advance a perspective of the entanglement issue that appeals to the Schlienz-Mahler measure [Phys. Rev. A 52, 4396 (1995)]. Related to it, we propose a criterium based on the consideration of convex subsets of quantum states. This criterium generalizes a property of product states to convex subsets (of the set of quantum states) that is able to uncover an interesting geometrical property of the separability property.
Spagnolo, Nicolo; Sciarrino, Fabio; De Martini, Francesco
2010-09-15
We show that the quantum states generated by universal optimal quantum cloning of a single photon represent a universal set of quantum superpositions resilient to decoherence. We adopt the Bures distance as a tool to investigate the persistence of quantum coherence of these quantum states. According to this analysis, the process of universal cloning realizes a class of quantum superpositions that exhibits a covariance property in lossy configuration over the complete set of polarization states in the Bloch sphere.
Finite groups and quantum physics
Kornyak, V. V.
2013-02-15
Concepts of quantum theory are considered from the constructive 'finite' point of view. The introduction of a continuum or other actual infinities in physics destroys constructiveness without any need for them in describing empirical observations. It is shown that quantum behavior is a natural consequence of symmetries of dynamical systems. The underlying reason is that it is impossible in principle to trace the identity of indistinguishable objects in their evolution-only information about invariant statements and values concerning such objects is available. General mathematical arguments indicate that any quantum dynamics is reducible to a sequence of permutations. Quantum phenomena, such as interference, arise in invariant subspaces of permutation representations of the symmetry group of a dynamical system. Observable quantities can be expressed in terms of permutation invariants. It is shown that nonconstructive number systems, such as complex numbers, are not needed for describing quantum phenomena. It is sufficient to employ cyclotomic numbers-a minimal extension of natural numbers that is appropriate for quantum mechanics. The use of finite groups in physics, which underlies the present approach, has an additional motivation. Numerous experiments and observations in the particle physics suggest the importance of finite groups of relatively small orders in some fundamental processes. The origin of these groups is unclear within the currently accepted theories-in particular, within the Standard Model.
Quantum well multijunction photovoltaic cell
Chaffin, Roger J.; Osbourn, Gordon C.
1987-01-01
A monolithic, quantum well, multilayer photovoltaic cell comprises a p-n junction comprising a p-region on one side and an n-region on the other side, each of which regions comprises a series of at least three semiconductor layers, all p-type in the p-region and all n-type in the n-region; each of said series of layers comprising alternating barrier and quantum well layers, each barrier layer comprising a semiconductor material having a first bandgap and each quantum well layer comprising a semiconductor material having a second bandgap when in bulk thickness which is narrower than said first bandgap, the barrier layers sandwiching each quantum well layer and each quantum well layer being sufficiently thin that the width of its bandgap is between said first and second bandgaps, such that radiation incident on said cell and above an energy determined by the bandgap of the quantum well layers will be absorbed and will produce an electrical potential across said junction.
Quantum well multijunction photovoltaic cell
Chaffin, R.J.; Osbourn, G.C.
1983-07-08
A monolithic, quantum well, multilayer photovoltaic cell comprises a p-n junction comprising a p-region on one side and an n-region on the other side, each of which regions comprises a series of at least three semiconductor layers, all p-type in the p-region and all n-type in the n-region; each of said series of layers comprising alternating barrier and quantum well layers, each barrier layer comprising a semiconductor material having a first bandgap and each quantum well layer comprising a semiconductor material having a second bandgap when in bulk thickness which is narrower than said first bandgap, the barrier layers sandwiching each quantum well layer and each quantum well layer being sufficiently thin that the width of its bandgap is between said first and second bandgaps, such that radiation incident on said cell and above an energy determined by the bandgap of the quantum well layers will be absorbed and will produce an electrical potential across said junction.
ASCR Workshop on Quantum Computing for Science
Aspuru-Guzik, Alan; Van Dam, Wim; Farhi, Edward; Gaitan, Frank; Humble, Travis; Jordan, Stephen; Landahl, Andrew J; Love, Peter; Lucas, Robert; Preskill, John; Muller, Richard P.; Svore, Krysta; Wiebe, Nathan; Williams, Carl
2015-06-01
This report details the findings of the DOE ASCR Workshop on Quantum Computing for Science that was organized to assess the viability of quantum computing technologies to meet the computational requirements of the DOEâ€™s science and energy mission, and to identify the potential impact of quantum technologies. The workshop was held on February 17-18, 2015, in Bethesda, MD, to solicit input from members of the quantum computing community. The workshop considered models of quantum computation and programming environments, physical science applications relevant to DOE's science mission as well as quantum simulation, and applied mathematics topics including potential quantum algorithms for linear algebra, graph theory, and machine learning. This report summarizes these perspectives into an outlook on the opportunities for quantum computing to impact problems relevant to the DOEâ€™s mission as well as the additional research required to bring quantum computing to the point where it can have such impact.
PURAC Limited | Open Energy Information
technology and project management company in the environment sector and specialising in water, wastewater and municpal waste treatment. References: PURAC Limited1 This article...
Lysanda Limited | Open Energy Information
CM8 3GA Product: US-based vehicle engineering consultancy with a technology capable of playing a role in vehicle emissions management. References: Lysanda Limited1 This...
Solfex Limited | Open Energy Information
Jump to: navigation, search Name: Solfex Limited Address: Energy Arena Bannister Hall Works Off Shop Lane, Higher Walton Preston, Lancashire PR5 4DZ Place: Preston, United...
History dependent quantum random walks as quantum lattice gas automata
Shakeel, Asif E-mail: dmeyer@math.ucsd.edu Love, Peter J. E-mail: dmeyer@math.ucsd.edu; Meyer, David A. E-mail: dmeyer@math.ucsd.edu
2014-12-15
Quantum Random Walks (QRW) were first defined as one-particle sectors of Quantum Lattice Gas Automata (QLGA). Recently, they have been generalized to include history dependence, either on previous coin (internal, i.e., spin or velocity) states or on previous position states. These models have the goal of studying the transition to classicality, or more generally, changes in the performance of quantum walks in algorithmic applications. We show that several history dependent QRW can be identified as one-particle sectors of QLGA. This provides a unifying conceptual framework for these models in which the extra degrees of freedom required to store the history information arise naturally as geometrical degrees of freedom on the lattice.
FUEL CASK IMPACT LIMITER VULNERABILITIES
Leduc, D; Jeffery England, J; Roy Rothermel, R
2009-02-09
Cylindrical fuel casks often have impact limiters surrounding just the ends of the cask shaft in a typical 'dumbbell' arrangement. The primary purpose of these impact limiters is to absorb energy to reduce loads on the cask structure during impacts associated with a severe accident. Impact limiters are also credited in many packages with protecting closure seals and maintaining lower peak temperatures during fire events. For this credit to be taken in safety analyses, the impact limiter attachment system must be shown to retain the impact limiter following Normal Conditions of Transport (NCT) and Hypothetical Accident Conditions (HAC) impacts. Large casks are often certified by analysis only because of the costs associated with testing. Therefore, some cask impact limiter attachment systems have not been tested in real impacts. A recent structural analysis of the T-3 Spent Fuel Containment Cask found problems with the design of the impact limiter attachment system. Assumptions in the original Safety Analysis for Packaging (SARP) concerning the loading in the attachment bolts were found to be inaccurate in certain drop orientations. This paper documents the lessons learned and their applicability to impact limiter attachment system designs.
Nontoxic quantum dot research improves solar cells
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
reported for any quantum dot solar cell," said Hunter McDaniel. Record power-conversion efficiency at Los Alamos from quantum-dot sensitized photovoltaics LOS ALAMOS, N.M., Dec....
Double logarithmic asymptotic behavior in quantum chromodynamics
Kirschner, R.
1981-08-01
The double logarithmic contributions to the quark-(anti)quark scattering and annihilation amplitudes are summed to all orders in quantum chromodynamics. The results are a generalization of the calculations of Gorshkov et al. in the case of quantum electrodynamics.
Quantum Process Matrix Computation by Monte Carlo
Energy Science and Technology Software Center (OSTI)
2012-09-11
The software package, processMC, is a python script that allows for the rapid modeling of small , noisy quantum systems and the computation of the averaged quantum evolution map.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
QKarD Quantum Smart Card QKarD Quantum Smart Card Los Alamos National Laboratory (LANL) scientists have developed a revolutionary technology entitled "QKarD" that implements the...
Super-radiance and open quantum systems
Volya, Alexander [Department of Physics, Florida State University, Tallahassee, FL 32306-4350 (United States); Zelevinsky, Vladimir [NSCL, Michigan State University, East Lansing, MI 48824-1321 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824-1321 (United States)
2005-07-08
Quantum wires, loosely bound nuclei, molecules in chemical reactions and exotic narrow pentaquark states are different examples of open quantum mesoscopic systems. The coupling with and through continuum is their common feature. We discuss general properties of quantum systems in the regime of strong continuum coupling, when the mechanism of Dicke super-radiance changes intrinsic dynamics, signatures of quantum chaos, lifetime of unstable states and reaction cross sections. The examples are shown for various areas of mesoscopic physics.
What the Blank Makes Quantum Dots Blink?
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
What the Blank Makes Quantum Dots Blink? What the Blank Makes Quantum Dots Blink? Calculations confirm that surface flaws are behind fluorescence intermittency in silicon nanocrystals June 15, 2015 Contact: Margie Wylie, mwylie@lbl.gov, +1 510 486 7421 Quantum dots are semiconductors just a few nanometers in diameter that can glow Quantum dots (shown here dissolved in liquid under ultraviolet light) offer tantalizing prospects for new technologies if scientists can stop them blinking. (Photo by
Nontoxic quantum dot research improves solar cells
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Nontoxic quantum dot research improves solar cells Nontoxic quantum dot research improves solar cells Solar cells made with low-cost, nontoxic copper-based quantum dots can achieve unprecedented longevity and efficiency, according to a study by LANL and Sharp Corporation. December 10, 2013 Hunter McDaniel, Los Alamos National Laboratory postdoctoral researcher, works in the laboratory developing next-generation quantum dots that could revolutionize photovoltaic technology. Hunter McDaniel, Los
Homogenization limit for a multiband effective mass model in heterostructures
Morandi, O.
2014-06-15
We study the homogenization limit of a multiband model that describes the quantum mechanical motion of an electron in a quasi-periodic crystal. In this approach, the distance among the atoms that constitute the material (lattice parameter) is considered a small quantity. Our model include the description of materials with variable chemical composition, intergrowth compounds, and heterostructures. We derive the effective multiband evolution system in the framework of the kp approach. We study the well posedness of the mathematical problem. We compare the effective mass model with the standard kp models for uniform and non-uniforms crystals. We show that in the limit of vanishing lattice parameter, the particle density obtained by the effective mass model, converges to the exact probability density of the particle.
Nuclear Structure at the Limits
Nazarewicz, W.
1998-01-12
One of the frontiers of today?s nuclear science is the ?journey to the limits? of atomic charge and nuclear mass, of neutron-to-proton ratio, and of angular momentum. The tour to the limits is not only a quest for new, exciting phenomena, but the new data are expected, as well, to bring qualitatively new information about the fundamental properties of the nucleonic many-body system, the nature of the nuclear interaction, and nucleonic correlations at various energy-distance scales. In this series of lectures, current developments in nuclear structure at the limits are discussed from a theoretical perspective, mainly concentrating on medium-mass and heavy nuclei.
Nuclear Structure at the Limits
Nazarewicz, Witold
1997-12-31
One of the frontiers of today`s nuclear science is the ``journey to the limits``: of atomic charge and nuclear mass, of neutron-to-proton ratio, and of angular momentum. The tour to the limits is not only a quest for new, exciting phenomena but the new data are expected, as well, to bring qualitatively new information about the fundamental properties of the nucleonic many-body system, the nature of the nuclear interaction, and nucleonic correlations at various energy-distance scales. In this talk, current developments in nuclear structure at the limits are discussed from a theoretical perspective.
Dose Limits | Department of Energy
Office of Environmental Management (EM)
Limits Dose Limits (Question Posted to ERAD in May 2012) Who do you define as a member of the public for the onsite MEI? This question implies that there may be more than one maximally exposed individual (MEI), one on-site and one off-site, when demonstrating compliance with the Public Dose Limit of DOE Order 458.1. Although all potential MEIs should be considered and documented, as well as the calculated doses and pathways considered, the intent of DOE Order 458.1 is in fact to ultimately
Quantum Indeterminacy of Cosmic Systems
Hogan, Craig J.
2013-12-30
It is shown that quantum uncertainty of motion in systems controlled mainly by gravity generally grows with orbital timescale $H^{-1}$, and dominates classical motion for trajectories separated by distances less than $\\approx H^{-3/5}$ in Planck units. For example, the cosmological metric today becomes indeterminate at macroscopic separations, $H_0^{-3/5}\\approx 60$ meters. Estimates suggest that entangled non-localized quantum states of geometry and matter may significantly affect fluctuations during inflation, and connect the scale of dark energy to that of strong interactions.
Plaxica Limited | Open Energy Information
Zip: SW7 2AZ Product: UK-based technology company developing a new generation of polymers derived from sustainable resources. References: Plaxica Limited1 This article is a...
Modulational instability of electromagnetic waves in a collisional quantum magnetoplasma
Niknam, A. R.; Rastbood, E.; Bafandeh, F.; Khorashadizadeh, S. M.
2014-04-15
The modulational instability of right-hand circularly polarized electromagnetic electron cyclotron (CPEM-EC) wave in a magnetized quantum plasma is studied taking into account the collisional effects. Employing quantum hydrodynamic and nonlinear Schrödinger equations, the dispersion relation of modulated CPEM-EC wave in a collisional plasma has been derived. It is found that this wave is unstable in such a plasma system and the growth rate of the associated instability depends on various parameters such as electron Fermi temperature, plasma number density, collision frequency, and modulation wavenumber. It is shown that while the increase of collision frequency leads to increase of the growth rate of instability, especially at large wavenumber limit, the increase of plasma number density results in more stable modulated CPEM-EC wave. It is also found that in contrast to collisionless plasma in which modulational instability is restricted to small wavenumbers, in collisional plasma, the interval of instability occurrence can be extended to a large domain.
Can the ring polymer molecular dynamics method be interpreted as real time quantum dynamics?
Jang, Seogjoo; Sinitskiy, Anton V.; Voth, Gregory A.
2014-04-21
The ring polymer molecular dynamics (RPMD) method has gained popularity in recent years as a simple approximation for calculating real time quantum correlation functions in condensed media. However, the extent to which RPMD captures real dynamical quantum effects and why it fails under certain situations have not been clearly understood. Addressing this issue has been difficult in the absence of a genuine justification for the RPMD algorithm starting from the quantum Liouville equation. To this end, a new and exact path integral formalism for the calculation of real time quantum correlation functions is presented in this work, which can serve as a rigorous foundation for the analysis of the RPMD method as well as providing an alternative derivation of the well established centroid molecular dynamics method. The new formalism utilizes the cyclic symmetry of the imaginary time path integral in the most general sense and enables the expression of Kubo-transformed quantum time correlation functions as that of physical observables pre-averaged over the imaginary time path. Upon filtering with a centroid constraint function, the formulation results in the centroid dynamics formalism. Upon filtering with the position representation of the imaginary time path integral, we obtain an exact quantum dynamics formalism involving the same variables as the RPMD method. The analysis of the RPMD approximation based on this approach clarifies that an explicit quantum dynamical justification does not exist for the use of the ring polymer harmonic potential term (imaginary time kinetic energy) as implemented in the RPMD method. It is analyzed why this can cause substantial errors in nonlinear correlation functions of harmonic oscillators. Such errors can be significant for general correlation functions of anharmonic systems. We also demonstrate that the short time accuracy of the exact path integral limit of RPMD is of lower order than those for finite discretization of path. The present quantum dynamics formulation also serves as the basis for developing new quantum dynamical methods that utilize the cyclic nature of the imaginary time path integral.
Passive fault current limiting device
Evans, D.J.; Cha, Y.S.
1999-04-06
A passive current limiting device and isolator is particularly adapted for use at high power levels for limiting excessive currents in a circuit in a fault condition such as an electrical short. The current limiting device comprises a magnetic core wound with two magnetically opposed, parallel connected coils of copper, a high temperature superconductor or other electrically conducting material, and a fault element connected in series with one of the coils. Under normal operating conditions, the magnetic flux density produced by the two coils cancel each other. Under a fault condition, the fault element is triggered to cause an imbalance in the magnetic flux density between the two coils which results in an increase in the impedance in the coils. While the fault element may be a separate current limiter, switch, fuse, bimetal strip or the like, it preferably is a superconductor current limiter conducting one-half of the current load compared to the same limiter wired to carry the total current of the circuit. The major voltage during a fault condition is in the coils wound on the common core in a preferred embodiment. 6 figs.
Passive fault current limiting device
Evans, Daniel J. (Wheeling, IL); Cha, Yung S. (Darien, IL)
1999-01-01
A passive current limiting device and isolator is particularly adapted for use at high power levels for limiting excessive currents in a circuit in a fault condition such as an electrical short. The current limiting device comprises a magnetic core wound with two magnetically opposed, parallel connected coils of copper, a high temperature superconductor or other electrically conducting material, and a fault element connected in series with one of the coils. Under normal operating conditions, the magnetic flux density produced by the two coils cancel each other. Under a fault condition, the fault element is triggered to cause an imbalance in the magnetic flux density between the two coils which results in an increase in the impedance in the coils. While the fault element may be a separate current limiter, switch, fuse, bimetal strip or the like, it preferably is a superconductor current limiter conducting one-half of the current load compared to the same limiter wired to carry the total current of the circuit. The major voltage during a fault condition is in the coils wound on the common core in a preferred embodiment.
High Efficiency Colloidal Quantum Dot Phosphors
Kahen, Keith
2013-12-31
The project showed that non-Cd containing, InP-based nanocrystals (semiconductor materials with dimensions of ~6 nm) have high potential for enabling next-generation, nanocrystal-based, on chip phosphors for solid state lighting. Typical nanocrystals fall short of the requirements for on chip phosphors due to their loss of quantum efficiency under the operating conditions of LEDs, such as, high temperature (up to 150 °C) and high optical flux (up to 200 W/cm2). The InP-based nanocrystals invented during this project maintain high quantum efficiency (>80%) in polymer-based films under these operating conditions for emission wavelengths ranging from ~530 to 620 nm. These nanocrystals also show other desirable attributes, such as, lack of blinking (a common problem with nanocrystals which limits their performance) and no increase in the emission spectral width from room to 150 °C (emitters with narrower spectral widths enable higher efficiency LEDs). Prior to these nanocrystals, no nanocrystal system (regardless of nanocrystal type) showed this collection of properties; in fact, other nanocrystal systems are typically limited to showing only one desirable trait (such as high temperature stability) but being deficient in other properties (such as high flux stability). The project showed that one can reproducibly obtain these properties by generating a novel compositional structure inside of the nanomaterials; in addition, the project formulated an initial theoretical framework linking the compositional structure to the list of high performance optical properties. Over the course of the project, the synthetic methodology for producing the novel composition was evolved to enable the synthesis of these nanomaterials at a cost approximately equal to that required for forming typical conventional nanocrystals. Given the above results, the last major remaining step prior to scale up of the nanomaterials is to limit the oxidation of these materials during the tens of thousands of hours of LED operation. Once the LED phosphor lifetime specifications are met, these nanocrystals will enable white LEDs for solid state lighting to simultaneously have increased efficiency and improved light quality, in addition to enabling the creation of custom light spectrums. These improvements to white LEDs will help accelerate the adoption of SSL, leading to large savings in US and worldwide energy costs.
Engineering Light: Quantum Cascade Lasers
Claire Gmachl
2010-09-01
Quantum cascade lasers are ideal for environmental sensing and medical diagnostic applications. Gmachl discusses how these lasers work, and their applications, including their use as chemical trace gas sensors. As examples of these applications, she briefly presents results from her field campaign at the Beijing Olympics, and ongoing campaigns in Texas, Maryland, and Ghana.
Naked singularities and quantum gravity
Harada, Tomohiro; Iguchi, Hideo; Nakao, Ken-ichi; Singh, T. P.; Tanaka, Takahiro; Vaz, Cenalo
2001-08-15
There are known models of spherical gravitational collapse in which the collapse ends in a naked shell-focusing singularity for some initial data. If a massless scalar field is quantized on the classical background provided by such a star, it is found that the outgoing quantum flux of the scalar field diverges in the approach to the Cauchy horizon. We argue that the semiclassical approximation (i.e., quantum field theory on a classical curved background) used in these analyses ceases to be valid about one Planck time before the epoch of naked singularity formation, because by then the curvature in the central region of the star reaches the Planck scale. It is shown that during the epoch in which the semiclassical approximation is valid, the total emitted energy is about one Planck unit, and is not divergent. We also argue that back reaction in this model does not become important so long as gravity can be treated classically. It follows that the further evolution of the star will be determined by quantum gravitational effects, and without invoking quantum gravity it is not possible to say whether the star radiates away on a short time scale or settles down into a black hole state.
Surface Induced Magnetism in Quantum Dots
Meulenberg, R W; Lee, J I
2009-08-20
The study of nanometer sized semiconductor crystallites, also known as quantum dots (QDs), has seen rapid advancements in recent years in scientific disciplines ranging from chemistry, physics, biology, materials science, and engineering. QD materials of CdSe, ZnSe, InP, as well as many others, can be prepared in the size range of 1-10 nm producing uniform, nearly monodisperse materials that are typically coated with organic molecules [1-3]. The strength of charge carrier confinement, which dictates the size-dependent properties, in these QDs depends on the nature of the material and can be correlated to the Bohr radius for the system of interest. For instance, the Bohr radius for CdSe is {approx} 5 nm, while in the more covalent structure of InP, the Bohr radius approaches {approx} 10 nm. The study of CdSe QDs has been particularly extensive during the last decade because they exhibit unique and tunable optical properties and are readily synthesized with high-crystallinity and narrow size dispersions. Although the core electronic properties of CdSe are explained in terms of the quantum confinement model, experimental efforts to elucidate the surface structure of these materials have been limited. Typically, colloidal CdSe QDs are coated with an organic surfactant, which typically consists of an organo-phosphine, -thiol, or -amine, that has the function of energetically relaxing defect states via coordination to partially coordinated surface atoms. The organic surfactant also acts to enhance carrier confinement and prevent agglomeration of the particles. Chemically, it has been shown that the bonding of the surfactant to the CdSe QD occurs through Cd atoms resulting cleavage of the Se atoms and formation of a Cd-rich (i.e. non-stoichiometric) particle [5].
Zurek, W.H. [Los Alamos National Lab., NM (United States); Pas, J.P. [Los Alamos National Lab., NM (United States)]|[Ciudad Universitaria (Argentina). Dept. de Fisica
1995-08-01
Violation of correspondence principle may occur for very macroscopic byt isolated quantum systems on rather short timescales as illustrated by the case of Hyperion, the chaotically tumbling moon of Saturn, for which quantum and classical predictions are expected to diverge on a timescale of approximately 20 years. Motivated by Hyperion, we review salient features of ``quantum chaos`` and show that decoherence is the essential ingredient of the classical limit, as it enables one to solve the apparent paradox caused by the breakdown of the correspondence principle for classically chaotic systems.
Voltage-controlled entanglement and quantum-information transfer between
Office of Scientific and Technical Information (OSTI)
spatially separated quantum-dot molecules (Journal Article) | SciTech Connect Voltage-controlled entanglement and quantum-information transfer between spatially separated quantum-dot molecules Citation Details In-Document Search Title: Voltage-controlled entanglement and quantum-information transfer between spatially separated quantum-dot molecules We propose two schemes for generating entanglement and quantum-state transfer (QST) between two spatially separated semiconductor quantum dot
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Biodiesel Limited Jump to: navigation, search Name: V-Fuels Biodiesel Limited Place: United Kingdom Product: UK-based biodiesel producers. References: V-Fuels Biodiesel Limited1...
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Belize Electricity Limited Jump to: navigation, search Logo: Belize Electricity Limited Name: Belize Electricity Limited Abbreviation: BEL Address: PO Box 327 Place: Belize City,...
Room-temperature quantum noise limited spectrometry and methods of the same
Stevens, Charles G.; Tringe, Joseph W.; Cunningham, Christopher Thomas
2014-08-26
In one embodiment, a heterodyne detection system for detecting light includes a first input aperture adapted for receiving first light from a scene input, a second input aperture adapted for receiving second light from a local oscillator input, a broadband local oscillator adapted for providing the second light to the second input aperture, a dispersive element adapted for dispersing the first light and the second light, and a final condensing lens coupled to an infrared detector. The final condensing lens is adapted for concentrating incident light from a primary condensing lens onto the infrared detector, and the infrared detector is a square-law detector capable of sensing the frequency difference between the first light and the second light. More systems and methods for detecting light are described according to other embodiments.
Room-temperature quantum noise limited spectrometry and methods of the same
Stevens, Charles G; Tringe, Joseph W
2014-12-02
In one embodiment, a heterodyne detection system for detecting light includes a first input aperture adapted for receiving a first light from a scene input, a second input aperture adapted for receiving a second light from a local oscillator input, a broadband local oscillator adapted for providing the second light to the second input aperture, a dispersive element adapted for dispersing the first light and the second light, and a final condensing lens coupled to an infrared detector. The final condensing lens is adapted for concentrating incident light from a primary condensing lens onto the detector, and the detector is a square-law detector capable of sensing the frequency difference between the first light and the second light. More systems and methods for detecting light are disclosed according to more embodiments.
Photocurrent extraction efficiency in colloidal quantum dot photovoltaics
Kemp, K. W.; Wong, C. T. O.; Hoogland, S. H.; Sargent, E. H.
2013-11-18
The efficiency of photocurrent extraction was studied directly inside operating Colloidal Quantum Dot (CQD) photovoltaic devices. A model was derived from first principles for a thin film p-n junction with a linearly spatially dependent electric field. Using this model, we were able to clarify the origins of recent improvement in CQD solar cell performance. From current-voltage diode characteristics under 1 sun conditions, we extracted transport lengths ranging from 39 nm to 86 nm for these materials. Characterization of the intensity dependence of photocurrent extraction revealed that the dominant loss mechanism limiting the transport length is trap-mediated recombination.
Quantum Dot Light Emitting Diode
Keith Kahen
2008-07-31
The project objective is to create low cost coatable inorganic light emitting diodes, composed of quantum dot emitters and inorganic nanoparticles, which have the potential for efficiencies equivalent to that of LEDs and OLEDs and lifetime, brightness, and environmental stability between that of LEDs and OLEDs. At the end of the project the Recipient shall gain an understanding of the device physics and properties of Quantum-Dot LEDs (QD-LEDs), have reliable and accurate nanocrystal synthesis routines, and have formed green-yellow emitting QD-LEDs with a device efficiency greater than 3 lumens/W, a brightness greater than 400 cd/m2, and a device operational lifetime of more than 1000 hours. Thus the aim of the project is to break the current cost-efficiency paradigm by creating novel low cost inorganic LEDs composed of inorganic nanoparticles.
Quantum Dot Light Emitting Diode
Kahen, Keith
2008-07-31
The project objective is to create low cost coatable inorganic light emitting diodes, composed of quantum dot emitters and inorganic nanoparticles, which have the potential for efficiencies equivalent to that of LEDs and OLEDs and lifetime, brightness, and environmental stability between that of LEDs and OLEDs. At the end of the project the Recipient shall gain an understanding of the device physics and properties of Quantum-Dot LEDs (QD-LEDs), have reliable and accurate nanocrystal synthesis routines, and have formed green-yellow emitting QD-LEDs with a device efficiency greater than 3 lumens/W, a brightness greater than 400 cd/m{sup 2}, and a device operational lifetime of more than 1000 hours. Thus the aim of the project is to break the current cost-efficiency paradigm by creating novel low cost inorganic LEDs composed of inorganic nanoparticles.
Quantum simulations of physics problems
Somma, R. D.; Ortiz, G.; Knill, E. H.; Gubernatis, J. E.
2003-01-01
If a large Quantum Computer (QC) existed today, what type of physical problems could we efficiently simulate on it that we could not efficiently simulate on a classical Turing machine? In this paper we argue that a QC could solve some relevant physical 'questions' more efficiently. The existence of one-to-one mappings between different algebras of observables or between different Hilbert spaces allow us to represent and imitate any physical system by any other one (e.g., a bosonic system by a spin-1/2 system). We explain how these mappings can be performed, and we show quantum networks useful for the efficient evaluation of some physical properties, such as correlation functions and energy spectra.
CORRELATIONS IN CONFINED QUANTUM PLASMAS
DUFTY J W
2012-01-11
This is the final report for the project 'Correlations in Confined Quantum Plasmas', NSF-DOE Partnership Grant DE FG02 07ER54946, 8/1/2007 - 7/30/2010. The research was performed in collaboration with a group at Christian Albrechts University (CAU), Kiel, Germany. That collaboration, almost 15 years old, was formalized during the past four years under this NSF-DOE Partnership Grant to support graduate students at the two institutions and to facilitate frequent exchange visits. The research was focused on exploring the frontiers of charged particle physics evolving from new experimental access to unusual states associated with confinement. Particular attention was paid to combined effects of quantum mechanics and confinement. A suite of analytical and numerical tools tailored to the specific inquiry has been developed and employed
NON-EQUILIBRIUM DYNAMICS OF MANY-BODY QUANTUM SYSTEMS: FUNDAMENTALS AND NEW FRONTIER
DeMille, David; LeHur, Karyn
2013-11-27
Rapid progress in nanotechnology and naofabrication techniques has ushered in a new era of quantum transport experiments. This has in turn heightened the interest in theoretical understanding of nonequilibrium dynamics of strongly correlated quantum systems. This project has advanced the frontiers of understanding in this area along several fronts. For example, we showed that under certain conditions, quantum impurities out of equilibrium can be reformulated in terms of an effective equilibrium theory; this makes it possible to use the gamut of tools available for quantum systems in equilibrium. On a different front, we demonstrated that the elastic power of a transmitted microwave photon in circuit QED systems can exhibit a many-body Kondo resonance. We also showed that under many circumstances, bipartite fluctuations of particle number provide an effective tool for studying many-body physics—particularly the entanglement properties of a many-body system. This implies that it should be possible to measure many-body entanglement in relatively simple and tractable quantum systems. In addition, we studied charge relaxation in quantum RC circuits with a large number of conducting channels, and elucidated its relation to Kondo models in various regimes. We also extended our earlier work on the dynamics of driven and dissipative quantum spin-boson impurity systems, deriving a new formalism that makes it possible to compute the full spin density matrix and spin-spin correlation functions beyond the weak coupling limit. Finally, we provided a comprehensive analysis of the nonequilibrium transport near a quantum phase transition in the case of a spinless dissipative resonant-level model. This project supported the research of two Ph.D. students and two postdoctoral researchers, whose training will allow them to further advance the field in coming years.
Quantum state of the multiverse
Robles-Perez, Salvador; Gonzalez-Diaz, Pedro F.
2010-04-15
A third quantization formalism is applied to a simplified multiverse scenario. A well-defined quantum state of the multiverse is obtained which agrees with standard boundary condition proposals. These states are found to be squeezed, and related to accelerating universes: they share similar properties to those obtained previously by Grishchuk and Siderov. We also comment on related works that have criticized the third quantization approach.
Entanglement across a transition to quantum chaos
Mejia-Monasterio, Carlos [Center for Nonlinear and Complex Systems, Universita degli Studi dell'Insubria, via Vallegio 11, Como 22100 (Italy); Benenti, Guliano; Casati, Giulio [Center for Nonlinear and Complex Systems, Universita degli Studi dell'Insubria, via Vallegio 11, Como 22100 (Italy); Istituto Nazionale per la Fisica della Materia, Unita di Como, via Vallegio 11, Como 22100 (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Milano, Via Celoria 16, 20133 Milan (Italy); Carlo, Gabriel G. [Center for Nonlinear and Complex Systems, Universita degli Studi dell'Insubria, via Vallegio 11, Como 22100 (Italy); Istituto Nazionale per la Fisica della Materia, Unita di Como, via Vallegio 11, Como 22100 (Italy)
2005-06-15
We study the relation between entanglement and quantum chaos in one- and two-dimensional spin-1/2 lattice models, which exhibit mixing of the noninteracting eigenfunctions and transition from integrability to quantum chaos. Contrary to what occurs in a quantum phase transition, the onset of quantum chaos is not a property of the ground state but takes place for any typical many-spin quantum state. We study bipartite and pairwise entanglement measures--namely, the reduced von Neumann entropy and the concurrence--and discuss quantum entanglement sharing. Our results suggest that the behavior of the entanglement is related to the mixing of the eigenfunctions rather than to the transition to chaos.
Tritium Detection Methods and Limitations
Office of Environmental Management (EM)
Detection Methods and Limitations Tritium Focus Group Meeting, April 2014 Tom Voss, Northern New Mexico DOE-HDBK-1105-2002 RADIOLOGICAL TRAINING FOR TRITIUM FACILITIES U.S. Department of Energy AREA TRNG Washington, D.C. 20585 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. DOE-HDBK-1105-2002 Radiological Training for Tritium Facilities U.S. Department of Energy, Radiological Control Programs for Special Tritium Compounds, DOE-STD- draft, Washington, D.C.
Optimum phase space probabilities from quantum tomography
Roy, Arunabha S.; Roy, S. M.
2014-01-15
We determine a positive normalised phase space probability distribution P with minimum mean square fractional deviation from the Wigner distribution W. The minimum deviation, an invariant under phase space rotations, is a quantitative measure of the quantumness of the state. The positive distribution closest to W will be useful in quantum mechanics and in time frequency analysis. The position-momentum correlations given by the distribution can be tested experimentally in quantum optics.
Gate fidelity fluctuations and quantum process invariants
Magesan, Easwar; Emerson, Joseph [Institute for Quantum Computing and Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Blume-Kohout, Robin [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2011-07-15
We characterize the quantum gate fidelity in a state-independent manner by giving an explicit expression for its variance. The method we provide can be extended to calculate all higher order moments of the gate fidelity. Using these results, we obtain a simple expression for the variance of a single-qubit system and deduce the asymptotic behavior for large-dimensional quantum systems. Applications of these results to quantum chaos and randomized benchmarking are discussed.
Quantum and Dirac Materials for Energy Applications
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Quantum and Dirac Materials Conference Quantum and Dirac Materials for Energy (QDM) Applications The purpose of the workshop is to discuss current status and future prospects for the quantum materials and Dirac materials for energy and information technology applications using recent advances in synthesis, characterization and modeling. Contact Institute Director Dr. Alexander V. Balatsky Institute for Materials Science (505) 665-0077 Email Deputy Director Dr. Jennifer S. Martinez Institute for
Kitaev models based on unitary quantum groupoids
Chang, Liang, E-mail: liangchang@math.tamu.edu [Department of Mathematics, Texas A and M University, College Station, Texas 77843-3368 (United States)] [Department of Mathematics, Texas A and M University, College Station, Texas 77843-3368 (United States)
2014-04-15
We establish a generalization of Kitaev models based on unitary quantum groupoids. In particular, when inputting a Kitaev-Kong quantum groupoid H{sub C}, we show that the ground state manifold of the generalized model is canonically isomorphic to that of the Levin-Wen model based on a unitary fusion category C. Therefore, the generalized Kitaev models provide realizations of the target space of the Turaev-Viro topological quantum field theory based on C.
Super-resolution with a positive epsilon multi-quantum-well super-lens
Bak, A. O.; Giannini, V.; Maier, S. A.; Phillips, C. C.
2013-12-23
We design an anisotropic and dichroic quantum metamaterial that is able to achieve super-resolution without the need for a negative permittivity. When exploring the parameters of the structure, we take into account the limits of semiconductor fabrication technology based on quantum well stacks. By heavily doping the structure with free electrons, we infer an anisotropic effective medium with a prolate ellipsoid dispersion curve which allows for near-diffractionless propagation of light (similar to an epsilon-near-zero hyperbolic lens). This, coupled with low absorption, allows us to resolve images at the sub-wavelength scale at distances 6?times greater than equivalent natural materials.
Ultrasensitive measurement of MEMS cantilever displacement sensitivity below the shot noise limit
Pooser, Raphael C; Lawrie, Benjamin J
2015-01-01
The displacement of micro-electro-mechanical-systems (MEMs) cantilevers is used to measure a variety of phe- nomena in devices ranging from force microscopes for single spin detection[1] to biochemical sensors[2] to un- cooled thermal imaging systems[3]. The displacement readout is often performed optically with segmented de- tectors or interference measurements. Until recently, var- ious noise sources have limited the minimum detectable displacement in MEMs systems, but it is now possible to minimize all other sources[4] so that the noise level of the coherent light eld, called the shot noise limit (SNL), becomes the dominant source. Light sources dis- playing quantum-enhanced statistics below this limit are available[5, 6], with applications in gravitational wave astronomy[7] and bioimaging[8], but direct displacement measurements of MEMS cantilevers below the SNL have been impossible until now. Here, we demonstrate the rst direct measurement of a MEMs cantilever displace- ment with sub-SNL sensitivity, thus enabling ultratrace sensing, imaging, and microscopy applications. By com- bining multi-spatial-mode quantum light sources with a simple dierential measurement, we show that sub-SNL MEMs displacement sensitivity is highly accessible com- pared to previous eorts that measured the displacement of macroscopic mirrors with very distinct spatial struc- tures crafted with multiple optical parametric ampliers and locking loops[9]. We apply this technique to a com- mercially available microcantilever in order to detect dis- placements 60% below the SNL at frequencies where the microcantilever is shot-noise-limited. These results sup- port a new class of quantum MEMS sensor whose ulti- mate signal to noise ratio is determined by the correla- tions possible in quantum optics systems.
Jeans stability in collisional quantum dusty magnetoplasmas
Jamil, M.; Asif, M.; Mir, Zahid; Salimullah, M.
2014-09-15
Jeans instability is examined in detail in uniform dusty magnetoplasmas taking care of collisional and non-zero finite thermal effects in addition to the quantum characteristics arising through the Bohm potential and the Fermi degenerate pressure using the quantum hydrodynamic model of plasmas. It is found that the presence of the dust-lower-hybrid wave, collisional effects of plasma species, thermal effects of electrons, and the quantum mechanical effects of electrons have significance over the Jeans instability. Here, we have pointed out a new class of dissipative instability in quantum plasma regime.
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing...
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Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Rotaxanes are mechanically interlocked molecular architectures consisting of a dumbbell-shaped molecule, the...
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Inc Jump to: navigation, search Name: Quantum Consulting Inc Place: Torrance, California Zip: 90505 Sector: Efficiency Product: Torrance-based energy consultancy, providing...
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s founders Jump to: navigation, search Name: Quantum Consulting's founders Place: Berkeley, California Product: Founders of the energy consulting firm that was originally based in...
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with NREL Yes Partnership Type Test & Evaluation Partner Partnering Center within NREL Science & Technology Partnership Year 2008 QuantumSphere is a company located in Santa Ana,...
Communication: Quantum molecular dynamics simulation of liquid...
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Communication: Quantum molecular dynamics simulation of liquid para-hydrogen by nuclear and electron wave packet approach Citation Details In-Document Search Title: Communication:...
ANALOG QUANTUM NEURON FOR FUNCTIONS APPROXIMATION (Conference...
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of Energy (US) Country of Publication: United States Language: English Subject: 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; IMPLEMENTATION; NERVE CELLS; WAVEGUIDES...
Enhanced optical limiting effects of graphene materials in polyimide
Gan, Yao; Feng, Miao; Zhan, Hongbing
2014-04-28
Three different graphene nanostructure suspensions of graphene oxide nanosheets (GONSs), graphene oxide nanoribbons (GONRs), and graphene oxide quantum dots (GOQDs) are prepared and characterized. Using a typical two-step method, the GONSs, GONRs, and GOQDs are incorporated into a polyimide (PI) matrix to synthesize graphene/PI composite films, whose nonlinear optical (NLO) and optical limiting (OL) properties are investigated at 532?nm in the nanosecond regime. The GONR suspension exhibits superior NLO and OL effects compared with those of GONSs and GOQDs because of its stronger nonlinear scattering and excited-state absorption. The graphene/PI composite films exhibit NLO and OL performance superior to that of their corresponding suspensions, which is attributed primarily to a combination of nonlinear mechanisms, charge transfer between graphene materials and PI, and the matrix effect.
Resonant tunnelling in a quantum oxide superlattice
Choi, Woo Seok; Lee, Sang A.; You, Jeong Ho; Lee, Suyoun; Lee, Ho Nyung
2015-06-24
Resonant tunneling is a quantum mechanical process that has long been attracting both scientific and technological attention owing to its intriguing underlying physics and unique applications for high-speed electronics. The materials system exhibiting resonant tunneling, however, has been largely limited to the conventional semiconductors, partially due to their excellent crystalline quality. Here we show that a deliberately designed transition metal oxide superlattice exhibits a resonant tunneling behaviour with a clear negative differential resistance. The tunneling occurred through an atomically thin, lanthanum Î´- doped SrTiO_{3} layer, and the negative differential resistance was realized on top of the bi-polar resistance switching typically observed for perovskite oxide junctions. This combined process resulted in an extremely large resistance ratio (~10^{5}) between the high and low resistance states. Lastly, the unprecedentedly large control found in atomically thin Î´-doped oxide superlattices can open a door to novel oxide-based high-frequency logic devices.
Resonant tunnelling in a quantum oxide superlattice
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Choi, Woo Seok; Lee, Sang A.; You, Jeong Ho; Lee, Suyoun; Lee, Ho Nyung
2015-06-24
Resonant tunneling is a quantum mechanical process that has long been attracting both scientific and technological attention owing to its intriguing underlying physics and unique applications for high-speed electronics. The materials system exhibiting resonant tunneling, however, has been largely limited to the conventional semiconductors, partially due to their excellent crystalline quality. Here we show that a deliberately designed transition metal oxide superlattice exhibits a resonant tunneling behaviour with a clear negative differential resistance. The tunneling occurred through an atomically thin, lanthanum Î´- doped SrTiO3 layer, and the negative differential resistance was realized on top of the bi-polar resistance switching typicallymoreÂ Â» observed for perovskite oxide junctions. This combined process resulted in an extremely large resistance ratio (~105) between the high and low resistance states. Lastly, the unprecedentedly large control found in atomically thin Î´-doped oxide superlattices can open a door to novel oxide-based high-frequency logic devices.Â«Â less
Gacs quantum algorithmic entropy in infinite dimensional Hilbert spaces
Benatti, Fabio, E-mail: benatti@ts.infn.it [Department of Physics, University of Trieste, Strada Costiera 11, I-34151 Trieste (Italy); Oskouei, Samad Khabbazi, E-mail: kh.oskuei@ut.ac.ir; Deh Abad, Ahmad Shafiei, E-mail: shafiei@khayam.ut.ac.ir [Department of Mathematics, School of Mathematics, Statistics and Computer Science, College of Science, University of Tehran, Tehran (Iran, Islamic Republic of)
2014-08-15
We extend the notion of Gacs quantum algorithmic entropy, originally formulated for finitely many qubits, to infinite dimensional quantum spin chains and investigate the relation of this extension with two quantum dynamical entropies that have been proposed in recent years.
Promising future of quantum dots explored in conference
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Promising future of quantum dots explored Promising future of quantum dots explored in conference Researchers are gathering to reflect on two decades of quantum dot research at a special topical conference, "20 Years of Quantum Dots at Los Alamos" April 13, 2015 Quantum dot LSC devices under ultraviolet illumination. Quantum dot LSC devices under ultraviolet illumination. Contact Los Alamos National Laboratory Nancy Ambrosiano Communications Office (505) 667-0471 Email "This
First-Ever Demonstration of Quantum Cryptography to Improve Security...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
First-Ever Demonstration of Quantum Cryptography to Improve Security of the Electric Grid First-Ever Demonstration of Quantum Cryptography to Improve Security of the Electric Grid...
Observation of a Macroscopically Quantum-Entangled Insulator
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matter, it could also have application to quantum computers because its information-processing properties would be insensitive to the presence of impurities, making quantum...
Quantum chaos and order based on classically moving reference frames
Hai Wenhua [Department of Physics, Hunan Normal University, Changsha 410081 (China); Department of Physics, Jishou University, Jishou 416000, Hunan (China); Xie Qiongtao; Fang Jianshu [Department of Physics, Hunan Normal University, Changsha 410081 (China)
2005-07-15
We develop a mathematically consistent approach for treating the quantum systems based on moving classical reference frames. The classical and quantum exact solutions show excellently classical-quantum correspondence, in which the quantum chaotic coherent states correspond to the classically chaotic motions. Applying the approach to the periodically driven linear and nonlinear oscillators, the regular and chaotic quantum states and quantum levels, and the quantum chaotic regions are evidenced. The results indicate that chaos may cause the collapse of matter wave packets and suppress the quantum effect of energy.
Generation of even harmonics in coupled quantum dots (Journal...
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Generation of even harmonics in coupled quantum dots Citation Details In-Document Search Title: Generation of even harmonics in coupled quantum dots Using the spatial-temporal...
Next-Generation "Giant" Quantum Dots: Performance-Engineered...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
"Giant" Quantum Dots: Performance-Engineered for Lighting Next-Generation "Giant" Quantum Dots: Performance-Engineered for Lighting Lead Performer: Los Alamos National Laboratory - ...
Deformation Quantization: Quantum Mechanic Lives and Works in...
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alternate, formulation of Quantum Mechanics, independent of the conventional Hilbert ... Language: English Subject: 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 73 NUCLEAR ...
Shiny quantum dots brighten future of solar cells
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Shiny quantum dots brighten future of solar cells Shiny quantum dots brighten future of solar ... dots can be applied in solar energy by helping more efficiently harvest sunlight. ...
Quantum Anomalous Hall Effect in 2D Organic Topological Insulators...
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Quantum Anomalous Hall Effect in 2D Organic Topological Insulators Citation Details In-Document Search Title: Quantum Anomalous Hall Effect in 2D Organic Topological Insulators ...
Dynamic trapping near a quantum critical point (Journal Article...
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Dynamic trapping near a quantum critical point Citation Details In-Document Search Title: Dynamic trapping near a quantum critical point Authors: Kolodrubetz, Michael ; Katz, ...
Microscopic theory of quantum anomalous Hall effect in graphene...
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Microscopic theory of quantum anomalous Hall effect in graphene Citation Details In-Document Search Title: Microscopic theory of quantum anomalous Hall effect in graphene Authors: ...
Universal Entanglement Entropy in 2D Conformal Quantum Critical...
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Title: Universal Entanglement Entropy in 2D Conformal Quantum Critical Points We study the scaling behavior of the entanglement entropy of two dimensional conformal quantum ...
Possible Bose-condensate Behavior in a Quantum Phase Originating...
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Possible Bose-condensate Behavior in a Quantum Phase Originating in a Collective ... Citation Details In-Document Search Title: Possible Bose-condensate Behavior in a Quantum ...
QUANTUM MECHANICS, GENERAL PHYSICS; 74 ATOMIC AND MOLECULAR PHYSICS...
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of model atoms in fields Milonni, P.W. 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 74 ATOMIC AND MOLECULAR PHYSICS; ATOMS; OPTICAL MODELS; QUANTUM MECHANICS;...
Topological one-way quantum computation on verified logical cluster...
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Subject: 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 97 MATHEMATICAL METHODS AND COMPUTING; CALCULATION METHODS; ERRORS; MATHEMATICAL LOGIC; NOISE; QUANTUM COMPUTERS; ...
Observation of a Macroscopically Quantum-Entangled Insulator
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A New Form of Macroscopic Quantum Weirdness One of the strangest consequences of quantum mechanics is the possibility of seemingly instantaneous communication between...
Open-System Adiabatic Quantum Annealing Bob Lucas USC - Lockheed...
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Open-System Adiabatic Quantum Annealing Bob Lucas USC - Lockheed Martin Quantum Computing Center April 29, 2015 Introduction | 2 Need More Capability? Application Specific Systems...
Observation of a Macroscopically Quantum-Entangled Insulator
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Observation of a Macroscopically Quantum-Entangled Insulator Observation of a Macroscopically Quantum-Entangled Insulator Print Wednesday, 27 May 2009 00:00 It has recently been...
Characterization of a swept external cavity quantum cascade laser...
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of a swept external cavity quantum cascade laser for rapid broadband spectroscopy and sensing Title: Characterization of a swept external cavity quantum cascade...
capture quantum correlations Qasimi, Asma Al-; James, Daniel...
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University of Toronto, Toronto, Ontario M5S 1A7 (Canada) 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ALGORITHMS; CAPTURE; ENTROPY; MIXED STATES; PURE STATES; QUANTUM...
Cost-Effective Fabrication Routes for the Production of Quantum...
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Production of Quantum Well Type Structures and Recovery of Waste Heat from Heavy Duty Trucks Cost-Effective Fabrication Routes for the Production of Quantum Well Type Structures ...
Quantum effects in the dynamics of deeply supercooled water ...
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Quantum effects in the dynamics of deeply supercooled water Citation Details In-Document Search Title: Quantum effects in the dynamics of deeply supercooled water Authors: Agapov, ...
Self-Referenced Continuous-Variable Quantum Key Distribution...
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Self-Referenced Continuous-Variable Quantum Key Distribution Protocol Citation Details In-Document Search Title: Self-Referenced Continuous-Variable Quantum Key Distribution ...
Quantum Oscillations in an Interfacial 2D Electron Gas. (Technical...
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Quantum Oscillations in an Interfacial 2D Electron Gas. Citation Details In-Document Search Title: Quantum Oscillations in an Interfacial 2D Electron Gas. Abstract not provided....
Quantum Anomalous Hall Effect in Hg_1-yMn_yTe Quantum Wells
Liu, Chao-Xing; Qi, Xiao-Liang; Dai, Xi; Fang, Zhong; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.
2010-03-19
The quantum Hall effect is usually observed when the two-dimensional electron gas is subjected to an external magnetic field, so that their quantum states form Landau levels. In this work we predict that a new phenomenon, the quantum anomalous Hall effect, can be realized in Hg{sub 1-y}Mn{sub y}Te quantum wells, without the external magnetic field and the associated Landau levels. This effect arises purely from the spin polarization of the Mn atoms, and the quantized Hall conductance is predicted for a range of quantum well thickness and the concentration of the Mn atoms. This effect enables dissipationless charge current in spintronics devices.
On-chip generation and guiding of quantum light from a site-controlled quantum dot
Jamil, Ayesha; Farrer, Ian; Griffiths, Jonathan P.; Jones, Geb A. C.; Ritchie, David A.; Skiba-Szymanska, Joanna; Kalliakos, Sokratis; Ward, Martin B.; Ellis, David J. P.; Shields, Andrew J.; Schwagmann, Andre; Brody, Yarden; Cambridge Research Laboratory, Toshiba Research Europe Limited, 208 Science Park, Milton Road, Cambridge, CB4 0GZ
2014-03-10
We demonstrate the emission and routing of single photons along a semiconductor chip originating from carrier recombination in an actively positioned InAs quantum dot. Device–scale arrays of quantum dots are formed by a two–step regrowth process. We precisely locate the propagating region of a unidirectional photonic crystal waveguide with respect to the quantum dot nucleation site. Under pulsed optical excitation, the multiphoton emission probability from the waveguide's exit is 12%?±?5% before any background correction. Our results are a major step towards the deterministic integration of a quantum emitter with the waveguiding components of photonic quantum circuits.
Semianalytical quantum model for graphene field-effect transistors
Pugnaghi, Claudio; Grassi, Roberto Gnudi, Antonio; Di Lecce, Valerio; Gnani, Elena; Reggiani, Susanna; Baccarani, Giorgio
2014-09-21
We develop a semianalytical model for monolayer graphene field-effect transistors in the ballistic limit. Two types of devices are considered: in the first device, the source and drain regions are doped by charge transfer with Schottky contacts, while, in the second device, the source and drain regions are doped electrostatically by a back gate. The model captures two important effects that influence the operation of both devices: (i) the finite density of states in the source and drain regions, which limits the number of states available for transport and can be responsible for negative output differential resistance effects, and (ii) quantum tunneling across the potential steps at the source-channel and drain-channel interfaces. By comparison with a self-consistent non-equilibrium Green's function solver, we show that our model provides very accurate results for both types of devices, in the bias region of quasi-saturation as well as in that of negative differential resistance.
Quantum chaos of atoms in a resonator driven by an external resonant field
Berman, G.P.; Bulgakov, E.N.; Holm, D.D. (Center for Nonlinear Studies, MS-B258, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States) Kirensky Institute of Physics, Research Educational Center for Nonlinear Processes at Krasnoyarsk Polytechnical Institute, Theoretical Department at Krasnoyarsk State University, 660036, Krasnoyarsk (Russian Federation) Theoretical Division, MS-B284, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States))
1994-06-01
A system of [ital N] two-level atoms in a resonator is considered interacting with a resonant eigenmode field and with an external coherent field, with a frequency slightly different from the frequency of the atomic transition. A model Hamiltonian is constructed for describing the slow quantum dynamics of the system, and a set of closed [ital c]-number equations for time-dependent quantum expectation values is derived in the boson and spin coherent states. In the region of parameters for developed chaos in the semiclassical limit (when the radiation field is considered classically) we show that the semiclassical approximation is violated by quantum effects at the time scale [tau][sub [h bar
Time-reversal symmetry breaking and the field theory of quantum chaos
Simons, B.D. [Cavendish Laboratory, Madingley Road, Cambridge, CB3 0HE (United Kingdom)] [Cavendish Laboratory, Madingley Road, Cambridge, CB3 0HE (United Kingdom); Agam, O. [NEC Research Institute, 4 Independence Way, Princeton, New Jersey 08540 (United States)] [NEC Research Institute, 4 Independence Way, Princeton, New Jersey 08540 (United States); Andreev, A.V. [Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States)] [Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States)
1997-04-01
Recent studies have shown that the quantum statistical properties of systems which are chaotic in their classical limit can be expressed in terms of an effective field theory. Within this description, spectral properties are determined by low energy relaxation modes of the classical evolution operator. It is in the interaction of these modes that quantum interference effects are encoded. In this paper we review this general approach and discuss how the theory is modified to account for time-reversal symmetry breaking. To keep our discussion general, we will also briefly describe how the theory is modified by the presence of an additional discrete symmetry such as inversion. Throughout, parallels are drawn between quantum chaotic systems and the properties of weakly disordered conductors. {copyright} {ital 1997 American Institute of Physics.}
Photocapacitance study of type-II GaSb/GaAs quantum ring solar cells
Wagener, M. C.; Botha, J. R.; Carrington, P. J.; Krier, A.
2014-01-07
In this study, the density of states associated with the localization of holes in GaSb/GaAs quantum rings are determined by the energy selective charging of the quantum ring distribution. The authors show, using conventional photocapacitance measurements, that the excess charge accumulated within the type-II nanostructures increases with increasing excitation energies for photon energies above 0.9?eV. Optical excitation between the localized hole states and the conduction band is therefore not limited to the ?(k?=?0) point, with pseudo-monochromatic light charging all states lying within the photon energy selected. The energy distribution of the quantum ring states could consequently be accurately related from the excitation dependence of the integrated photocapacitance. The resulting band of localized hole states is shown to be well described by a narrow distribution centered 407?meV above the GaAs valence band maximum.
Dynamical bifurcation as a semiclassical counterpart of a quantum phase transition
Buonsante, P.; Vezzani, A.
2011-12-15
We illustrate how dynamical transitions in nonlinear semiclassical models can be recognized as phase transitions in the corresponding--inherently linear--quantum model, where, in a statistical-mechanics framework, the thermodynamic limit is realized by letting the particle population go to infinity at fixed size. We focus on lattice bosons described by the Bose-Hubbard (BH) model and discrete self-trapping (DST) equations at the quantum and semiclassical levels, respectively. After showing that the Gaussianity of the quantum ground states is broken at the phase transition, we evaluate finite-population effects by introducing a suitable scaling hypothesis; we work out the exact value of the critical exponents and provide numerical evidence confirming our hypothesis. Our analytical results rely on a general scheme obtained from a large-population expansion of the eigenvalue equation of the BH model. In this approach the DST equations resurface as solutions of the zeroth-order problem.
Thick-shell nanocrystal quantum dots
Hollingsworth, Jennifer A. (Los Alamos, NM); Chen, Yongfen (Eugene, OR); Klimov, Victor I. (Los Alamos, NM); Htoon, Han (Los Alamos, NM); Vela, Javier (Los Alamos, NM)
2011-05-03
Colloidal nanocrystal quantum dots comprising an inner core having an average diameter of at least 1.5 nm and an outer shell, where said outer shell comprises multiple monolayers, wherein at least 30% of the quantum dots have an on-time fraction of 0.80 or greater under continuous excitation conditions for a period of time of at least 10 minutes.
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Limited (Nufcor) Place: United Kingdom Sector: Services Product: UK-based uranium marketing services company. References: Nufcor International Limited (Nufcor)1 This article...
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Limited-life cartridge primers
Makowiecki, Daniel M. (Livermore, CA); Rosen, Robert S. (San Ramon, CA)
1998-01-01
A cartridge primer which utilizes an explosive that can be designed to become inactive in a predetermined period of time: a limited-life primer. The explosive or combustible material of the primer is an inorganic reactive multilayer (RML). The reaction products of the RML are sub-micron grains of non-corrosive inorganic compounds that would have no harmful effects on firearms or cartridge cases. Unlike use of primers containing lead components, primers utilizing RML's would not present a hazard to the environment. The sensitivity of an RML is determined by the physical structure and the stored interfacial energy. The sensitivity lowers with time due to a decrease in interfacial energy resulting from interdiffusion of the elemental layers. Time-dependent interdiffusion is predictable, thereby enabling the functional lifetime of an RML primer to be predetermined by the initial thickness and materials selection of the reacting layers.
Limited-life cartridge primers
Makowiecki, Daniel M.; Rosen, Robert S.
2005-04-19
A cartridge primer which utilizes an explosive that can be designed to become inactive in a predetermined period of time: a limited-life primer. The explosive or combustible material of the primer is an inorganic reactive multilayer (RML). The reaction products of the RML are sub-micron grains of non-corrosive inorganic compounds that would have no harmful effects on firearms or cartridge cases. Unlike use of primers containing lead components, primers utilizing RML's would not present a hazard to the environment. The sensitivity of an RML is determined by the physical structure and the stored interfacial energy. The sensitivity lowers with time due to a decrease in interfacial energy resulting from interdiffusion of the elemental layers. Time-dependent interdiffusion is predictable, thereby enabling the functional lifetime of an RML primer to be predetermined by the initial thickness and materials selection of the reacting layers.
Limited-life cartridge primers
Makowiecki, D.M.; Rosen, R.S.
1998-06-30
A cartridge primer is described which utilizes an explosive that can be designed to become inactive in a predetermined period of time: a limited-life primer. The explosive or combustible material of the primer is an inorganic reactive multilayer (RML). The reaction products of the RML are sub-micron grains of non-corrosive inorganic compounds that would have no harmful effects on firearms or cartridge cases. Unlike use of primers containing lead components, primers utilizing RML`s would not present a hazard to the environment. The sensitivity of an RML is determined by the physical structure and the stored interfacial energy. The sensitivity lowers with time due to a decrease in interfacial energy resulting from interdiffusion of the elemental layers. Time-dependent interdiffusion is predictable, thereby enabling the functional lifetime of an RML primer to be predetermined by the initial thickness and materials selection of the reacting layers. 10 figs.
Materials Frontiers to Empower Quantum Computing
Taylor, Antoinette Jane; Sarrao, John Louis; Richardson, Christopher
2015-06-11
This is an exciting time at the nexus of quantum computing and materials research. The materials frontiers described in this report represent a significant advance in electronic materials and our understanding of the interactions between the local material and a manufactured quantum state. Simultaneously, directed efforts to solve materials issues related to quantum computing provide an opportunity to control and probe the fundamental arrangement of matter that will impact all electronic materials. An opportunity exists to extend our understanding of materials functionality from electronic-grade to quantum-grade by achieving a predictive understanding of noise and decoherence in qubits and their origins in materials defects and environmental coupling. Realizing this vision systematically and predictively will be transformative for quantum computing and will represent a qualitative step forward in materials prediction and control.
Shear wall ultimate drift limits
Duffey, T.A.; Goldman, A.; Farrar, C.R.
1994-04-01
Drift limits for reinforced-concrete shear walls are investigated by reviewing the open literature for appropriate experimental data. Drift values at ultimate are determined for walls with aspect ratios ranging up to a maximum of 3.53 and undergoing different types of lateral loading (cyclic static, monotonic static, and dynamic). Based on the geometry of actual nuclear power plant structures exclusive of containments and concerns regarding their response during seismic (i.e.,cyclic) loading, data are obtained from pertinent references for which the wall aspect ratio is less than or equal to approximately 1, and for which testing is cyclic in nature (typically displacement controlled). In particular, lateral deflections at ultimate load, and at points in the softening region beyond ultimate for which the load has dropped to 90, 80, 70, 60, and 50 percent of its ultimate value, are obtained and converted to drift information. The statistical nature of the data is also investigated. These data are shown to be lognormally distributed, and an analysis of variance is performed. The use of statistics to estimate Probability of Failure for a shear wall structure is illustrated.
Quantum ion-acoustic wave oscillations in metallic nanowires
Moradi, Afshin
2015-05-15
The low-frequency electrostatic waves in metallic nanowires are studied using the quantum hydrodynamic model, in which the electron and ion components of the system are regarded as a two-species quantum plasma system. The Poisson equation as well as appropriate quantum boundary conditions give the analytical expressions of dispersion relations of the surface and bulk quantum ion-acoustic wave oscillations.
Quantum measurements of atoms using cavity QED
Dada, Adetunmise C.; Andersson, Erika [SUPA, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Jones, Martin L.; Kendon, Vivien M. [School of Physics and Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT (United Kingdom); Everitt, Mark S. [School of Physics and Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT (United Kingdom); National Institute of Informatics, 2-1-2 Hitotsubashi, Chiyoda ku, Tokyo 101-8430 (Japan)
2011-04-15
Generalized quantum measurements are an important extension of projective or von Neumann measurements in that they can be used to describe any measurement that can be implemented on a quantum system. We describe how to realize two nonstandard quantum measurements using cavity QED. The first measurement optimally and unambiguously distinguishes between two nonorthogonal quantum states. The second example is a measurement that demonstrates superadditive quantum coding gain. The experimental tools used are single-atom unitary operations effected by Ramsey pulses and two-atom Tavis-Cummings interactions. We show how the superadditive quantum coding gain is affected by errors in the field-ionization detection of atoms and that even with rather high levels of experimental imperfections, a reasonable amount of superadditivity can still be seen. To date, these types of measurements have been realized only on photons. It would be of great interest to have realizations using other physical systems. This is for fundamental reasons but also since quantum coding gain in general increases with code word length, and a realization using atoms could be more easily scaled than existing realizations using photons.
Orbital ferromagnetism and the Chandrasekhar mass-limit
Akbari-Moghanjoughi, M.
2012-05-15
In this paper, we use quantum magnetohydrodynamic as well as magnetohydrostatic (MHS) models for a zero-temperature Fermi-Dirac plasma to show the fundamental role of Landau orbital ferromagnetism (LOFER) on the magnetohydrostatic stability of compact stars. It is revealed that the generalized flux-conserved equation of state of form B={beta}{rho}{sup 2s/3} only with conditions 0{<=}s{<=}1 and 0{<=}{beta}<{radical}(2{pi}) can lead to a stable compact stellar configuration. The distinct critical value {beta}{sub cr}={radical}(2{pi}) is shown to affect the magnetohydrostatic stability of the LOFER (s = 1) state and the magnetic field strength limit on the compact stellar configuration. Furthermore, the value of the parameter {beta} is remarked to fundamentally alter the Chandrasekhar mass-radius relation and the known mass-limit on white dwarfs when the star is in LOFER state. Current findings can help to understand the role of flux-frozen ferromagnetism and its fundamental role on hydrostatic stability of relativistically degenerate super-dense plasmas such as white dwarfs.
Superfluid {sup 4}He Quantum Interference Grating
Sato, Yuki; Joshi, Aditya; Packard, Richard
2008-08-22
We report the first observation of quantum interference from a grating structure consisting of four weak link junctions in superfluid {sup 4}He. We find that an interference grating can be implemented successfully in a superfluid matter wave interferometer to enhance its sensitivity while trading away some of its dynamic range. We also show that this type of device can be used to measure absolute quantum mechanical phase differences. The results demonstrate the robust nature of superfluid phase coherence arising from quantum mechanics on a macroscopic scale.
Towards bulk based preconditioning for quantum dotcomputations
Dongarra, Jack; Langou, Julien; Tomov, Stanimire; Channing,Andrew; Marques, Osni; Vomel, Christof; Wang, Lin-Wang
2006-05-25
This article describes how to accelerate the convergence of Preconditioned Conjugate Gradient (PCG) type eigensolvers for the computation of several states around the band gap of colloidal quantum dots. Our new approach uses the Hamiltonian from the bulk materials constituent for the quantum dot to design an efficient preconditioner for the folded spectrum PCG method. The technique described shows promising results when applied to CdSe quantum dot model problems. We show a decrease in the number of iteration steps by at least a factor of 4 compared to the previously used diagonal preconditioner.
Resonator-quantum well infrared photodetectors
Choi, K. K. Sun, J.; Olver, K.; Jhabvala, M. D.; Jhabvala, C. A.; Waczynski, A.
2013-11-11
We applied a recent electromagnetic model to design the resonator-quantum well infrared photodetector (R-QWIP). In this design, we used an array of rings as diffractive elements to diffract normal incident light into parallel propagation and used the pixel volume as a resonator to intensify the diffracted light. With a proper pixel size, the detector resonates at certain optical wavelengths and thus yields a high quantum efficiency (QE). To test this detector concept, we fabricated a number of R-QWIPs with different quantum well materials and detector geometries. The experimental result agrees satisfactorily with the prediction, and the highest QE achieved is 71%.
A quantum measure of the multiverse
Vilenkin, Alexander
2014-05-01
It has been recently suggested that probabilities of different events in the multiverse are given by the frequencies at which these events are encountered along the worldline of a geodesic observer (the ''watcher''). Here I discuss an extension of this probability measure to quantum theory. The proposed extension is gauge-invariant, as is the classical version of this measure. Observations of the watcher are described by a reduced density matrix, and the frequencies of events can be found using the decoherent histories formalism of Quantum Mechanics (adapted to open systems). The quantum watcher measure makes predictions in agreement with the standard Born rule of QM.
Time-dependent density functional theory quantum transport simulation in non-orthogonal basis
Kwok, Yan Ho; Xie, Hang; Yam, Chi Yung; Chen, Guan Hua; Zheng, Xiao
2013-12-14
Basing on the earlier works on the hierarchical equations of motion for quantum transport, we present in this paper a first principles scheme for time-dependent quantum transport by combining time-dependent density functional theory (TDDFT) and Keldysh's non-equilibrium Green's function formalism. This scheme is beyond the wide band limit approximation and is directly applicable to the case of non-orthogonal basis without the need of basis transformation. The overlap between the basis in the lead and the device region is treated properly by including it in the self-energy and it can be shown that this approach is equivalent to a lead-device orthogonalization. This scheme has been implemented at both TDDFT and density functional tight-binding level. Simulation results are presented to demonstrate our method and comparison with wide band limit approximation is made. Finally, the sparsity of the matrices and computational complexity of this method are analyzed.
Surface plasmon oscillations on a quantum plasma half-space
Moradi, Afshin
2015-01-15
We investigate the propagation of surface electrostatic oscillations on a quantum plasma half-space, taking into account the quantum effects. We derive the quantum surface wave frequencies of the system, by means the quantum hydrodynamic theory in conjunction with the Poisson equation and applying the appropriate additional quantum boundary conditions. Numerical results show in the presence of the slow nonlocal variations, plasmon wave energies of the system are significantly modified and plasmonic oscillations with blue-shifted frequencies emerge.
Universal Entanglement Entropy in 2D Conformal Quantum Critical Points
Office of Scientific and Technical Information (OSTI)
(Journal Article) | SciTech Connect Universal Entanglement Entropy in 2D Conformal Quantum Critical Points Citation Details In-Document Search Title: Universal Entanglement Entropy in 2D Conformal Quantum Critical Points We study the scaling behavior of the entanglement entropy of two dimensional conformal quantum critical systems, i.e. systems with scale invariant wave functions. They include two-dimensional generalized quantum dimer models on bipartite lattices and quantum loop models, as
Integrability and nonintegrability of quantum systems. II. Dynamics in quantum phase space
Zhang, Weimin (Department of Physics, FM-15, University of Washington, Seattle, WA (USA) Department of Physics and Atmospheric Science, Drexel University, Philadelphia, PA (USA)); Feng, D.H.; Yuan, Jianmin (Department of Physics and Atmospheric Science, Drexel University, Philadelphia, PA (USA))
1990-12-15
Based on the concepts of integrability and nonintegrability of a quantum system presented in a previous paper (Zhang, Feng, Yuan, and Wang, Phys. Rev. A 40, 438 (1989)), a realization of the dynamics in the quantum phase space is now presented. For a quantum system with dynamical group {ital G-script} and in one of its unitary irreducible-representation carrier spaces {ital h-german}{sub {Lambda}}, the quantum phase space is a 2{ital M}{sub {Lambda}}-dimensional topological space, where {ital M}{sub {Lambda}} is the quantum-dynamical degrees of freedom. This quantum phase space is isomorphic to a coset space {ital G-script}/{ital H-script} via the unitary exponential mapping of the elementary excitation operator subspace of {ital g-script} (algebra of {ital G-script}), where {ital H-script} ({contained in}{ital G-script}) is the maximal stability subgroup of a fixed state in {ital h-german}{sub {Lambda}}. The phase-space representation of the system is realized on {ital G-script}/{ital H-script}, and its classical analogy can be obtained naturally. It is also shown that there is consistency between quantum and classical integrability. Finally, a general algorithm for seeking the manifestation of quantum chaos'' via the classical analogy is provided. Illustrations of this formulation in several important quantum systems are presented.
Optical spectroscopy of quantum confined states in GaAs/AlGaAs quantum well tubes
Shi, Teng; Fickenscher, Melodie; Smith, Leigh; Jackson, Howard; Yarrison-Rice, Jan; Gao, Qiang; Tan, Hoe; Jagadish, Chennupati; Etheridge, Joanne; Wong, Bryan M.
2013-12-04
We have investigated the quantum confinement of electronic states in GaAs/Al{sub x}Ga{sub 1?x}As nanowire heterostructures which contain radial GaAs quantum wells of either 4nm or 8nm. Photoluminescence and photoluminescence excitation spectroscopy are performed on single nanowires. We observed emission and excitation of electron and hole confined states. Numerical calculations of the quantum confined states using the detailed structural information on the quantum well tubes show excellent agreement with these optical results.
Analytical results from the quantum theory of a single-emitter nanolaser
Larionov, Nikolay V.; Kolobov, Mikhail I.
2011-11-15
We provide analytical results obtained in the framework of the quantum theory for a single-emitter nanolaser: an incoherently pumped single two-level system interacting with a single-cavity mode of finite finesse. In the good-cavity limit we analytically calculate the linewidth of such a laser, its amplitude fluctuation spectrum, and the intracavity Mandel Q parameter. Our analytical results are in very good agreement with numerical simulations of the master equation.
An uncertainty principle for unimodular quantum groups
Crann, Jason; Kalantar, Mehrdad E-mail: mkalanta@math.carleton.ca
2014-08-15
We present a generalization of Hirschman's entropic uncertainty principle for locally compact Abelian groups to unimodular locally compact quantum groups. As a corollary, we strengthen a well-known uncertainty principle for compact groups, and generalize the relation to compact quantum groups of Kac type. We also establish the complementarity of finite-dimensional quantum group algebras. In the non-unimodular setting, we obtain an uncertainty relation for arbitrary locally compact groups using the relative entropy with respect to the Haar weight as the measure of uncertainty. We also show that when restricted to q-traces of discrete quantum groups, the relative entropy with respect to the Haar weight reduces to the canonical entropy of the random walk generated by the state.
Software-defined Quantum Communication Systems
Humble, Travis S; Sadlier, Ronald J
2014-01-01
Quantum communication systems harness modern physics through state-of-the-art optical engineering to provide revolutionary capabilities. An important concern for quantum communication engineering is designing and prototyping these systems to prototype proposed capabilities. We apply the paradigm of software-defined communica- tion for engineering quantum communication systems to facilitate rapid prototyping and prototype comparisons. We detail how to decompose quantum communication terminals into functional layers defining hardware, software, and middleware concerns, and we describe how each layer behaves. Using the super-dense coding protocol as a test case, we describe implementations of both the transmitter and receiver, and we present results from numerical simulations of the behavior. We find that while the theoretical benefits of super dense coding are maintained, there is a classical overhead associated with the full implementation.
Non-abelian fractional quantum hall effect for fault-resistant...
Office of Scientific and Technical Information (OSTI)
Non-abelian fractional quantum hall effect for fault-resistant topological quantum computation. Citation Details In-Document Search Title: Non-abelian fractional quantum hall...
Ultrabroad stimulated emission from quantum well laser
Wang, Huolei; Zhou, Xuliang; Yu, Hongyan; Mi, Junping; Wang, Jiaqi; Bian, Jing; Wang, Wei; Pan, Jiaoqing; Ding, Ying; Chen, Weixi
2014-06-23
Observation of ultrabroad stimulated emission from a simplex quantum well based laser at the center wavelength of 1.06??m is reported. With increased injection current, spectrum as broad as 38?nm and a pulsed output power of ?50?mW have been measured. The experiments show evidence of an unexplored broad emission regime in the InGaAs/GaAs quantum well material system, which still needs theoretical modeling and further analysis.
Sandia National Laboratories: Advances toward quantum computing
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
By Neal Singer Photography By Randy Montoya Thursday, March 03, 2016 Precise atom implants in silicon provide first step toward quantum computers Precise atom implants in silicon provide first step toward quantum computers Post-doc fellows Meenakshi Singh and Jose Pacheco stand in front of Sandia's ion beam generator. Project PI Meenakshi holds a sample qubit structure embedded in silicon. (Photo by Randy Montoya) Sandia researchers have supported post-doctoral fellow Meenakshi Singh (1132) in
First principle thousand atom quantum dot calculations
Wang, Lin-Wang; Li, Jingbo
2004-03-30
A charge patching method and an idealized surface passivation are used to calculate the single electronic states of IV-IV, III-V, II-VI semiconductor quantum dots up to a thousand atoms. This approach scales linearly and has a 1000 fold speed-up compared to direct first principle methods with a cost of eigen energy error of about 20 meV. The calculated quantum dot band gaps are parametrized for future references.
Galilei invariant technique for quantum system description
Kamuntavi?ius, Gintautas P.
2014-04-15
Problems with quantum systems models, violating Galilei invariance are examined. The method for arbitrary non-relativistic quantum system Galilei invariant wave function construction, applying a modified basis where center-of-mass excitations have been removed before Hamiltonian matrix diagonalization, is developed. For identical fermion system, the Galilei invariant wave function can be obtained while applying conventional antisymmetrization methods of wave functions, dependent on single particle spatial variables.
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing?
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Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Wednesday, 26 August 2009 00:00 Rotaxanes are mechanically interlocked molecular architectures consisting of a dumbbell-shaped molecule, the "axle," that threads through a ring called a macrocycle. Because the rings can spin around and slide along the axle, rotaxanes are promising components of molecular machines. While most rotaxanes have been entirely
GenDrive Limited | Open Energy Information
GenDrive Limited Jump to: navigation, search Name: GenDrive Limited Place: Cambridge, United Kingdom Zip: CB23 3GY Sector: Renewable Energy, Solar, Wind energy Product: Developing...
Mistral Invest Limited | Open Energy Information
Mistral Invest Limited Jump to: navigation, search Name: Mistral Invest Limited Place: London, United Kingdom Zip: W1U 7DW Sector: Wind energy Product: Private Equity Fund aiming...
Biodiesel Energy Trading Limited | Open Energy Information
Limited Jump to: navigation, search Name: Biodiesel Energy Trading Limited Place: London, United Kingdom Zip: W1J 8DY Product: London-based company focused on trading of biodiesel....
Graduate Program Time Limits and Work Schedules
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Time Limits and Work Schedules Graduate Program Time Limits and Work Schedules Point your career towards Los Alamos Lab: work with the best minds on the planet in an inclusive...
Undergraduate Program Time Limits and Work Schedules
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Time Limits and Work Schedules Undergraduate Program Time Limits and Work Schedules Point your career towards Los Alamos Lab: work with the best minds on the planet in an inclusive...
IT Power Limited | Open Energy Information
IT Power Limited Jump to: navigation, search Name: IT Power Limited Place: Basingstoke, England, United Kingdom Zip: RG24 8AG Sector: Renewable Energy Product: IT Power is a...
Lead Hero Limited | Open Energy Information
Hero Limited Jump to: navigation, search Name: Lead Hero Limited Place: China Product: China-based company that holds a 100% interest in XiAn Lv Jing and a 15.05% interest in...
EU Energy Wind Limited | Open Energy Information
Wind Limited Jump to: navigation, search Name: EU Energy (Wind) Limited Place: Central Milton Keynes, United Kingdom Zip: K9 1LH Sector: Wind energy Product: The company will be...
Zebec Biogas Limited | Open Energy Information
Zebec Biogas Limited Jump to: navigation, search Name: Zebec Biogas Limited Place: Glasgow, Scotland, United Kingdom Zip: G12 9JD Product: Sotland-based biogas company. The firm is...
Fractional quantum Hall junctions and two-channel Kondo models
Sandler, Nancy P.; Fradkin, Eduardo
2001-06-15
A mapping between fractional quantum Hall (FQH) junctions and the two-channel Kondo model is presented. We discuss this relation in detail for the particular case of a junction of a FQH state at {nu}=1/3 and a normal metal. We show that in the strong coupling regime this junction has a non-Fermi-liquid fixed point. At this fixed point the electron Green{close_quote}s function has a branch cut and the impurity entropy is equal to S=1/2ln2. We construct the space of perturbations at the strong coupling fixed point and find that the dimension of the tunneling operator is 1/2. These properties are strongly reminiscent of the non-Fermi-liquid fixed points of a number of quantum impurity models, particularly the two-channel Kondo model. However we have found that, in spite of these similarities, the Hilbert spaces of these two systems are quite different. In particular, although in a special limit the Hamiltonians of both systems are the same, their Hilbert spaces are not since they are determined by physically distinct boundary conditions. As a consequence the spectrum of operators in the two problems is different.
Colloidal quantum dot solar cells on curved and flexible substrates
Kramer, Illan J.; Moreno-Bautista, Gabriel; Minor, James C.; Kopilovic, Damir; Sargent, Edward H.
2014-10-20
Colloidal quantum dots (CQDs) are semiconductor nanocrystals synthesized with, processed in, and deposited from the solution phase, potentially enabling low-cost, facile manufacture of solar cells. Unfortunately, CQD solar cell reports, until now, have only explored batch-processing methods—such as spin-coating—that offer limited capacity for scaling. Spray-coating could offer a means of producing uniform colloidal quantum dot films that yield high-quality devices. Here, we explore the versatility of the spray-coating method by producing CQD solar cells in a variety of previously unexplored substrate arrangements. The potential transferability of the spray-coating method to a roll-to-roll manufacturing process was tested by spray-coating the CQD active layer onto six substrates mounted on a rapidly rotating drum, yielding devices with an average power conversion efficiency of 6.7%. We further tested the manufacturability of the process by endeavoring to spray onto flexible substrates, only to find that spraying while the substrate was flexed was crucial to achieving champion performance of 7.2% without compromise to open-circuit voltage. Having deposited onto a substrate with one axis of curvature, we then built our CQD solar cells onto a spherical lens substrate having two axes of curvature resulting in a 5% efficient device. These results show that CQDs deposited using our spraying method can be integrated to large-area manufacturing processes and can be used to make solar cells on unconventional shapes.
Exorka International Limited | Open Energy Information
Exorka International Limited is a specialist developer of low-temperature geothermal electricity generation, incorporated in England. References: Exorka International...
Undergraduate Program Time Limits and Work Schedules
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Time Limits and Work Schedules Undergraduate Program Time Limits and Work Schedules Point your career towards Los Alamos Lab: work with the best minds on the planet in an inclusive environment that is rich in intellectual vitality and opportunities for growth. Contact Student Programs (505) 665-8899 Email Time limits The length of participation in the undergraduate program is limited to a maximum of six years for students pursuing a bachelor's degree and three years for students pursuing an
Limited English Proficiency | Department of Energy
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Limited English Proficiency Limited English Proficiency On August 11, 2000, President Clinton signed Executive Order 13166, "Improving Access to Services for Persons with Limited English Proficiency." The Executive Order requires federal agencies, including the Department of Energy, to examine the programs and services they provide, to determine whether there is a need for language assistance for persons with Limited English proficiency (LEP) related to their programs and services, and
Ultra Thin Quantum Well Materials
Dr Saeid Ghamaty
2012-08-16
This project has enabled Hi-Z technology Inc. (Hi-Z) to understand how to improve the thermoelectric properties of Si/SiGe Quantum Well Thermoelectric Materials. The research that was completed under this project has enabled Hi-Z Technology, Inc. (Hi-Z) to satisfy the project goal to understand how to improve thermoelectric conversion efficiency and reduce costs by fabricating ultra thin Si/SiGe quantum well (QW) materials and measuring their properties. In addition, Hi-Z gained critical new understanding on how thin film fabrication increases the silicon substrate's electrical conductivity, which is important new knowledge to develop critical material fabrication parameters. QW materials are constructed with alternate layers of an electrical conductor, SiGe and an electrical insulator, Si. Film thicknesses were varied, ranging from 2nm to 10nm where 10 nm was the original film thickness prior to this work. The optimum performance was determined at a Si and SiGe thickness of 4nm for an electrical current and heat flow parallel to the films, which was an important conclusion of this work. Essential new information was obtained on how the Si substrate electrical conductivity increases by up to an order of magnitude upon deposition of QW films. Test measurements and calculations are accurate and include both the quantum well and the substrate. The large increase in substrate electrical conductivity means that a larger portion of the electrical current passes through the substrate. The silicon substrate's increased electrical conductivity is due to inherent impurities and thermal donors which are activated during both molecular beam epitaxy and sputtering deposition of QW materials. Hi-Z's forward looking cost estimations based on future high performance QW modules, in which the best Seebeck coefficient and electrical resistivity are taken from separate samples predict that the electricity cost produced with a QW module could be achieved at <$0.35/W. This price would open many markets for waste heat recovery applications. By installing Hi-Z's materials in applications in which electricity could be produced from waste heat sources could result in significant energy savings as well as emissions reductions. For example, if QW thermoelectric generators could be introduced commercially in 2015, and assuming they could also capture an additional 0.1%/year of the available waste heat from the aluminum, steel, and iron industries, then by 2020, their use would lead to a 2.53 trillion Btu/year reduction in energy consumption. This translates to a $12.9 million/year energy savings, and 383.6 million lb's of CO2 emissions reduction per year. Additionally, Hi-Z would expect that the use of QW TE devices in the automotive, manufacturing, and energy generation industries would reduce the USA's petroleum and fossil fuel dependence, and thus significantly reduce emissions from CO2 and other polluting gasses such as NOx, SOx, and particulate matter (PM), etc.
Primordial magnetic field limits from cosmological data
Kahniashvili, Tina [McWilliams Center for Cosmology and Department of Physics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213 (United States); Department of Physics, Laurentian University, Ramsey Lake Road, Sudbury, Ontario P3E 2C (Canada); Abastumani Astrophysical Observatory, Ilia State University, 2A Kazbegi Ave, Tbilisi, GE-0160 (Georgia); Tevzadze, Alexander G. [Abastumani Astrophysical Observatory, Ilia State University, 2A Kazbegi Ave, Tbilisi, GE-0160 (Georgia); Faculty of Exact and Natural Sciences, Tbilisi State University, 1 Chavchavadze Avenue, Tbilisi, GE-0128 (Georgia); Sethi, Shiv K. [McWilliams Center for Cosmology and Department of Physics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213 (United States); Raman Research Institute, Sadashivanagar, Bangalore 560080 (India); Pandey, Kanhaiya [Raman Research Institute, Sadashivanagar, Bangalore 560080 (India); Ratra, Bharat [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States)
2010-10-15
We study limits on a primordial magnetic field arising from cosmological data, including that from big bang nucleosynthesis, cosmic microwave background polarization plane Faraday rotation limits, and large-scale structure formation. We show that the physically relevant quantity is the value of the effective magnetic field, and limits on it are independent of how the magnetic field was generated.
High temperature superconducting fault current limiter
Hull, John R.
1997-01-01
A fault current limiter (10) for an electrical circuit (14). The fault current limiter (10) includes a high temperature superconductor (12) in the electrical circuit (14). The high temperature superconductor (12) is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter (10).
High temperature superconducting fault current limiter
Hull, J.R.
1997-02-04
A fault current limiter for an electrical circuit is disclosed. The fault current limiter includes a high temperature superconductor in the electrical circuit. The high temperature superconductor is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter. 15 figs.
Hyperspectral Microscopy of Explosives Particles Using an External Cavity Quantum Cascade Laser
Phillips, Mark C.; Bernacki, Bruce E.
2012-12-26
Using infrared hyperspectral imaging, we demonstrate microscopy of small particles of the explosives compounds RDX, tetryl, and PETN with near diffraction-limited performance. The custom microscope apparatus includes an external cavity quantum cascade laser illuminator scanned over its tuning range of 9.13-10.53 µm in four seconds, coupled with a microbolometer focal plane array to record infrared transmission images. We use the hyperspectral microscopy technique to study the infrared absorption spectra of individual explosives particles, and demonstrate sub-nanogram detection limits.
Nonlocal microscopic theory of quantum friction between parallel metallic slabs
Despoja, Vito
2011-05-15
We present a new derivation of the friction force between two metallic slabs moving with constant relative parallel velocity, based on T=0 quantum-field theory formalism. By including a fully nonlocal description of dynamically screened electron fluctuations in the slab, and avoiding the usual matching-condition procedure, we generalize previous expressions for the friction force, to which our results reduce in the local limit. Analyzing the friction force calculated in the two local models and in the nonlocal theory, we show that for physically relevant velocities local theories using the plasmon and Drude models of dielectric response are inappropriate to describe friction, which is due to excitation of low-energy electron-hole pairs, which are properly included in nonlocal theory. We also show that inclusion of dissipation in the nonlocal electronic response has negligible influence on friction.
The von Neumann model of measurement in quantum mechanics
Mello, Pier A.
2014-01-08
We describe how to obtain information on a quantum-mechanical system by coupling it to a probe and detecting some property of the latter, using a model introduced by von Neumann, which describes the interaction of the system proper with the probe in a dynamical way. We first discuss single measurements, where the system proper is coupled to one probe with arbitrary coupling strength. The goal is to obtain information on the system detecting the probe position. We find the reduced density operator of the system, and show how Lüders rule emerges as the limiting case of strong coupling. The von Neumann model is then generalized to two probes that interact successively with the system proper. Now we find information on the system by detecting the position-position and momentum-position correlations of the two probes. The so-called 'Wigner's formula' emerges in the strong-coupling limit, while 'Kirkwood's quasi-probability distribution' is found as the weak-coupling limit of the above formalism. We show that successive measurements can be used to develop a state-reconstruction scheme. Finally, we find a generalized transform of the state and the observables based on the notion of successive measurements.
Quantum dynamics of solid Ne upon photo-excitation of a NO impurity: A Gaussian wave packet approach
Unn-Toc, W.; Meier, C.; Halberstadt, N.; Uranga-Pina, Ll.; Rubayo-Soneira, J.
2012-08-07
A high-dimensional quantum wave packet approach based on Gaussian wave packets in Cartesian coordinates is presented. In this method, the high-dimensional wave packet is expressed as a product of time-dependent complex Gaussian functions, which describe the motion of individual atoms. It is applied to the ultrafast geometrical rearrangement dynamics of NO doped cryogenic Ne matrices after femtosecond laser pulse excitation. The static deformation of the solid due to the impurity as well as the dynamical response after femtosecond excitation are analyzed and compared to reduced dimensionality studies. The advantages and limitations of this method are analyzed in the perspective of future applications to other quantum solids.
Quantum chaos in one dimension?
Ujfalusi, Laszlo; Varga, Imre; Schumayer, Daniel [Elmeleti Fizika Tanszek, Fizikai Intezet, Budapesti Muszaki es Gazdasagtudomanyi Egyetem, H-1521 Budapest (Hungary); Department of Physics, University of Otago, 730 Cumberland Street, Dunedin 9016 (New Zealand)
2011-07-15
In this work we investigate the inverse of the celebrated Bohigas-Giannoni-Schmit conjecture. Using two inversion methods we compute a one-dimensional potential whose lowest N eigenvalues obey random matrix statistics. Our numerical results indicate that in the asymptotic limit N{yields}{infinity} the solution is nowhere differentiable and most probably nowhere continuous. Thus such a counterexample does not exist.
Quantum nonlocal effects on optical properties of spherical nanoparticles
Moradi, Afshin
2015-02-15
To study the scattering of electromagnetic radiation by a spherical metallic nanoparticle with quantum spatial dispersion, we develop the standard nonlocal Mie theory by allowing for the excitation of the quantum longitudinal plasmon modes. To describe the quantum nonlocal effects, we use the quantum longitudinal dielectric function of the system. As in the standard Mie theory, the electromagnetic fields are expanded in terms of spherical vector wavefunctions. Then, the usual Maxwell boundary conditions are imposed plus the appropriate additional boundary conditions. Examples of calculated extinction spectra are presented, and it is found that the frequencies of the subsidiary peaks, due to quantum bulk plasmon excitations exhibit strong dependence on the quantum spatial dispersion.
Near-Infrared Localized Surface Plasmon Resonances Arising from Free Carriers in Doped Quantum Dots
Jain, Prashant K.; Luther, Joey; Ewers, Trevor; Alivisatos, A. Paul
2010-10-12
Quantum confinement of electronic wavefunctions in semiconductor quantum dots (QDs) yields discrete atom-like and tunable electronic levels, thereby allowing the engineering of excitation and emission spectra. Metal nanoparticles, on the other hand, display strong resonant interactions with light from localized surface plasmon resonance (LSPR) oscillations of free carriers, resulting in enhanced and geometrically tunable absorption and scattering resonances. The complementary attributes of these nanostructures lends strong interest toward integration into hybrid nanostructures to explore enhanced properties or the emergence of unique attributes arising from their interaction. However, the physicochemical interface between the two components can be limiting for energy transfer and synergistic coupling within such a hybrid nanostructure. Therefore, it is advantageous to realize both attributes, i.e., LSPRs and quantum confinement within the same nanostructure. Here, we describe well-defined LSPRs arising from p-type carriers in vacancy-doped semiconductor quantum dots. This opens up possibilities for light harvesting, non-linear optics, optical sensing and manipulation of solid-state processes in single nanocrystals.
Quantum superposition principle and gravitational collapse: Scattering times for spherical shells
Ambrus, M.; Hajicek, P.
2005-09-15
A quantum theory of spherically symmetric thin shells of null dust and their gravitational field is studied. In Nucl. Phys. B603, 555 (2001), it has been shown how superpositions of quantum states with different geometries can lead to a solution of the singularity problem and black hole information paradox: the shells bounce and re-expand and the evolution is unitary. The corresponding scattering times will be defined in the present paper. To this aim, a spherical mirror of radius R{sub m} is introduced. The classical formula for scattering times of the shell reflected from the mirror is extended to quantum theory. The scattering times and their spreads are calculated. They have a regular limit for R{sub m}{yields}0 and they reveal a resonance at E{sub m}=c{sup 4}R{sub m}/2G. Except for the resonance, they are roughly of the order of the time the light needs to cross the flat space distance between the observer and the mirror. Some ideas are discussed of how the construction of the quantum theory could be changed so that the scattering times become considerably longer.
Santa Fe New Mexican: For cybersecurity, in quantum encryption we trust
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For cybersecurity, in quantum encryption we trust Santa Fe New Mexican: For cybersecurity, in quantum encryption we trust Los Alamos physicists developed a quantum random number generator and a quantum communication system, which exploit the laws of quantum physics to improve cybersecurity. September 13, 2015 Los Alamos physicists developed a quantum random number generator and a quantum communication system, both of which exploit the weird and immutable laws of quantum physics to improve
Performance limits of plasmon-enhanced organic photovoltaics
Karatay, Durmus U.; Ginger, David S.; Salvador, Michael; Yao, Kai; Jen, Alex K.-Y.
2014-07-21
We use a combination of experiment and modeling to explore the promise and limitations of using plasmon-resonant metal nanoparticles to enhance the device performance of organic photovoltaics (OPVs). We focus on optical properties typical of the current generation of low-bandgap donor polymers blended with the fullerene (6,6)-phenyl C{sub 71}-butyric acid methyl ester (PC{sub 71}BM) and use the polymer poly(indacenodithiophene-co-phenanthro[9,10-b]quinoxaline) (PIDT-PhanQ) as our test case. We model the optical properties and performance of these devices both in the presence and absence of a variety of colloidal silver nanoparticles. We show that for these materials, device performance is sensitive to the relative z-position and the density of nanoparticles inside the active layer. Using conservative estimates of the internal quantum efficiency for the PIDT-PhanQ/PC{sub 71}BM blend, we calculate that optimally placed silver nanoparticles could yield an enhancement in short-circuit current density of over 31% when used with???80-nm-thick active layers, resulting in an absolute increase in power conversion efficiency of up to ?2% for the device based on optical engineering.
Maharashtra State Power Generation Company Limited MAHAGENCO...
search Name: Maharashtra State Power Generation Company Limited (MAHAGENCO) Place: Mumbai, Maharashtra, India Zip: 400051 Product: Power generating firm planning to set up a...
Wedotebary Nigeria Limited | Open Energy Information
Name: Wedotebary Nigeria Limited Place: Bukuru, Nigeria Product: Nigeria-based manufacturing conglomerate. Coordinates: 9.79017, 8.85481 Show Map Loading map......
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Greater London, United Kingdom Zip: GU21 5JY Product: EVO Electric Limited develops electrical motors and generators for use in gensets, powertrains, and traction motors in...
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Technology Limited (ATL) Place: N.T., Hong Kong Product: Designer and manufacturer of Lithium Ion Polymer (LIP) battery cells and batteries for OEM customers making cell phones,...
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as a consultant advising on renewable energy technologies, energy efficiency, & corporate social responsibility. References: CarbonPlan Limited1 This article is a stub. You can...
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Place: Lahore, Pakistan Sector: Solar Product: Yarn manufacturer, plans to set up solar thermal plant. References: Colony Mills Limited1 This article is a stub. You can help...
Graduate Program Time Limits and Work Schedules
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Time Limits and Work Schedules Graduate Program Time Limits and Work Schedules Point your career towards Los Alamos Lab: work with the best minds on the planet in an inclusive environment that is rich in intellectual vitality and opportunities for growth. Contact Student Programs (505) 665-0987 Email Time Limits The length of participation in the graduate program is limited as follows: With a bachelor's pursuing a master's degree: 4 years With a bachelor's pursuing a PhD: 7 years With a master's
12 Voltz Limited | Open Energy Information
Limited Place: Cumbria, United Kingdom Zip: LA8 9NH Sector: Renewable Energy, Solar, Wind energy Product: Selling and delivering broad range of advanced energy generating...
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storage product manufacturer; also makes lighting systems based on solar, wind and solar wind hybrid systems. References: Caldyne Automatics Limited1 This article is a stub....
Power Paper Limited | Open Energy Information
Jump to: navigation, search Name: Power Paper Limited Place: Kiryat Arye, Petah Tikva, Israel Zip: 49130 Product: Power Paper is a developer of next-generation, printable...
Hydrogenation of Dislocation-Limited Heteroepitaxial Silicon...
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Hydrogenation of Dislocation- Limited Heteroepitaxial Silicon Solar Cells Preprint Michael L. Bolen, Sachit Grover, Charles W. Teplin, Howard M. Branz, and Paul Stradins National...
Hydrogenation of Dislocation-Limited Heteroepitaxial Silicon...
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Hydrogenation of Dislocation-Limited Heteroepitaxial Silicon Solar Cells: Preprint Bolen, M. L.; Grover, S.; Teplin, C. W.; Bobela, D.; Branz, H. M.; Stradins, P. 08 HYDROGEN; 14...
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Place: Shijiazhuang, Hebei Province, China Zip: 50011 Sector: Hydro Product: China-based small hydro project developer. References: Hebei Hydroelectric Company Limited1 This...
Royal Energy Limited REL | Open Energy Information
(REL) Place: Mumbai, Maharashtra, India Zip: 400 016 Product: Mumbai-based ethanol and biodiesel producer. References: Royal Energy Limited (REL)1 This article is a stub. You...
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Carnegie Wave Energy Limited | Open Energy Information
Limited Address: 1 124 Stirling Highway Place: North Fremantle Zip: 6159 Region: Australia Sector: Marine and Hydrokinetic Year Founded: 1993 Website: www.carnegiewave.com...
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Energy Limited Place: Lucknow, Uttar Pradesh, India Product: Uttar Pradesh-based joint venture company for the production, procurement, cultivation and plantation of crops...
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United Kingdom Sector: Biomass Product: UK-based biomass firm developing anaerobic digestion plants. References: Local Generation Limited1 This article is a stub. You can help...
Interim Guidance Regarding Limitations on CERCLA Liability |...
search OpenEI Reference LibraryAdd to library PermittingRegulatory Guidance - Inner-Office Memorandum: Interim Guidance Regarding Limitations on CERCLA LiabilityPermitting...
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United Kingdom Zip: SY16 2LW Sector: Services Product: Provides operational and maintenance services in Cumbria, Cornwall and Wales. References: Cumbria Wind Farms Limited1...
Proactive Energy Limited | Open Energy Information
Energy Product: Scotland-based renewable energy company that is developing a 5MW biogas plant in South Lanarkshire. References: Proactive Energy Limited1 This article is a...
GP Batteries International Limited | Open Energy Information
International Limited is principally engaged in the development, manufacture and marketing of batteries and battery-related products. References: GP Batteries International...
Green Heat Solutions Limited | Open Energy Information
to: navigation, search Name: Green Heat Solutions Limited Region: Scotland Sector: Marine and Hydrokinetic Website: http: This company is listed in the Marine and Hydrokinetic...
Vihaan Networks Limited VNL | Open Energy Information
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Quantum-mechanical aspects of classically chaotic driven systems
Milonni, P.W.; Ackerhalt, J.R.; Goggin, M.E.
1987-01-01
This paper treats atoms and molecules in laser fields as periodically driven quantum systems. The paper concludes by determining that stochastic excitation is possible in quantum systems with quasiperiodic driving. 17 refs. (JDH)
Surface treatment of nanocrystal quantum dots after film deposition
Sykora, Milan; Koposov, Alexey; Fuke, Nobuhiro
2015-02-03
Provided are methods of surface treatment of nanocrystal quantum dots after film deposition so as to exchange the native ligands of the quantum dots for exchange ligands that result in improvement in charge extraction from the nanocrystals.
Spin-orbit interaction in multiple quantum wells
Hao, Ya-Fei
2015-01-07
In this paper, we investigate how the structure of multiple quantum wells affects spin-orbit interactions. To increase the interface-related Rashba spin splitting and the strength of the interface-related Rashba spin-orbit interaction, we designed three kinds of multiple quantum wells. We demonstrate that the structure of the multiple quantum wells strongly affected the interface-related Rashba spin-orbit interaction, increasing the interface-related Rashba spin splitting to up to 26% larger in multiple quantum wells than in a stepped quantum well. We also show that the cubic Dresselhaus spin-orbit interaction similarly influenced the spin relaxation time of multiple quantum wells and that of a stepped quantum well. The increase in the interface-related Rashba spin splitting originates from the relationship between interface-related Rashba spin splitting and electron probability density. Our results suggest that multiple quantum wells can be good candidates for spintronic devices.
Sandia Energy - Sandia Develops a Synthesis of Quantum Dots that...
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Develops a Synthesis of Quantum Dots that Increases the Quantum Yield to 95.5% Home Energy Solid-State Lighting Office of Science News Energy Efficiency News & Events Research &...
Quantum and Dirac Materials for Energy Applications Conference...
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Quantum and Dirac Materials for Energy Applications Quantum and Dirac Materials for Energy Applications Conference (QDM-15) WHEN: Mar 08, 2015 8:00 AM - Mar 11, 2015 5:00 PM WHERE:...
Cost-Effective Fabrication Routes for the Productionof Quantum...
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Productionof Quantum-Well-Type Structures and Recovoery of Waste Heat from Heavy-Duty Trucks Cost-Effective Fabrication Routes for the Productionof Quantum-Well-Type Structures and ...
Berman, G.P. [Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Bulgakov, E.N. [Kirensky Institute of Physics, 660036, Krasnoyarsk (Russia)] [Kirensky Institute of Physics, 660036, Krasnoyarsk (Russia); Campbell, D.K. [Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801-3080 (United States)] [Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801-3080 (United States); Krive, I.V. [Institute for Low Temperature Physics and Engineering, Ukrainian Academy of Sciences, 310164, Kharkov (Ukraine)] [Institute for Low Temperature Physics and Engineering, Ukrainian Academy of Sciences, 310164, Kharkov (Ukraine)
1997-10-01
We consider Aharonov-Bohm oscillations in a mesoscopic semiconductor ring threaded by both a constant magnetic flux and a time-dependent, resonant magnetic field with one or two frequencies. Working in the ballistic regime, we establish that the theory of {open_quotes}quantum nonlinear resonance{close_quotes} applies, and thus that this system represents a possible solid-state realization of {open_quotes}quantum nonlinear resonance{close_quotes} and {open_quotes}quantum chaos.{close_quotes} In particular, we investigate the behavior of the time-averaged electron energy at zero temperature in the regimes of (i) an isolated quantum nonlinear resonance and (ii) the transition to quantum chaos, when two quantum nonlinear resonances overlap. The time-averaged energy exhibits sharp resonant behavior as a function of the applied constant magnetic flux, and has a staircase dependence on the amplitude of the external time-dependent field. In the chaotic regime, the resonant behavior exhibits complex structure as a function of flux and frequency. We compare and contrast the quantum chaos expected in these mesoscopic {open_quotes}solid-state atoms{close_quotes} with that observed in Rydberg atoms in microwave fields, and discuss the prospects for experimental observation of the effects we predict. {copyright} {ital 1997} {ital The American Physical Society}
Association of scattering matrices in quantum networks
Almeida, F.A.G.; Macędo, A.M.S.
2013-06-15
Algorithms based on operations that associate scattering matrices in series or in parallel (analogous to impedance association in a classical circuit) are developed here. We exemplify their application by calculating the total scattering matrix of several types of quantum networks, such as star graphs and a chain of chaotic quantum dots, obtaining results with good agreement with the literature. Through a computational-time analysis we compare the efficiency of two algorithms for the simulation of a chain of chaotic quantum dots based on series association operations of (i) two-by-two centers and (ii) three-by-three ones. Empirical results point out that the algorithm (ii) is more efficient than (i) for small number of open scattering channels. A direct counting of floating point operations justifies quantitatively the superiority of the algorithm (i) for large number of open scattering channels.
Multichannel framework for singular quantum mechanics
Camblong, Horacio E.; Epele, Luis N.; Fanchiotti, Huner; García Canal, Carlos A.; Ordóńez, Carlos R.
2014-01-15
A multichannel S-matrix framework for singular quantum mechanics (SQM) subsumes the renormalization and self-adjoint extension methods and resolves its boundary-condition ambiguities. In addition to the standard channel accessible to a distant (“asymptotic”) observer, one supplementary channel opens up at each coordinate singularity, where local outgoing and ingoing singularity waves coexist. The channels are linked by a fully unitary S-matrix, which governs all possible scenarios, including cases with an apparent nonunitary behavior as viewed from asymptotic distances. -- Highlights: •A multichannel framework is proposed for singular quantum mechanics and analogues. •The framework unifies several established approaches for singular potentials. •Singular points are treated as new scattering channels. •Nonunitary asymptotic behavior is subsumed in a unitary multichannel S-matrix. •Conformal quantum mechanics and the inverse quartic potential are highlighted.
Quantum singularities in the BTZ spacetime
Pitelli, Joao Paulo M.; Letelier, Patricio S.
2008-06-15
The spinless Banados-Teiltelboim-Zanelli spacetime is considered in the quantum theory context. Specifically, we study the case of a negative mass parameter using quantum test particles obeying the Klein-Gordon and Dirac equations. We study if this classical singular spacetime, with a naked singularity at the origin, remains singular when tested with quantum particles. The need for additional information near the origin is confirmed for massive scalar particles and all of the possible boundary conditions necessary to turn the spatial portion of the wave operator self-adjoint are found. When tested by massless scalar particles or fermions, the singularity is ''healed'' and no extra boundary condition is needed. Near infinity, no boundary conditions are necessary.
Exciton binding energy in semiconductor quantum dots
Pokutnii, S. I.
2010-04-15
In the adiabatic approximation in the context of the modified effective mass approach, in which the reduced exciton effective mass {mu} = {mu}(a) is a function of the radius a of the semiconductor quantum dot, an expression for the exciton binding energy E{sub ex}(a) in the quantum dot is derived. It is found that, in the CdSe and CdS quantum dots with the radii a comparable to the Bohr exciton radii a{sub ex}, the exciton binding energy E{sub ex}(a) is substantially (respectively, 7.4 and 4.5 times) higher than the exciton binding energy in the CdSe and CdS single crystals.
Quantum cryptographic system with reduced data loss
Lo, Hoi-Kwong; Chau, Hoi Fung
1998-01-01
A secure method for distributing a random cryptographic key with reduced data loss. Traditional quantum key distribution systems employ similar probabilities for the different communication modes and thus reject at least half of the transmitted data. The invention substantially reduces the amount of discarded data (those that are encoded and decoded in different communication modes e.g. using different operators) in quantum key distribution without compromising security by using significantly different probabilities for the different communication modes. Data is separated into various sets according to the actual operators used in the encoding and decoding process and the error rate for each set is determined individually. The invention increases the key distribution rate of the BB84 key distribution scheme proposed by Bennett and Brassard in 1984. Using the invention, the key distribution rate increases with the number of quantum signals transmitted and can be doubled asymptotically.
Quantum cryptographic system with reduced data loss
Lo, H.K.; Chau, H.F.
1998-03-24
A secure method for distributing a random cryptographic key with reduced data loss is disclosed. Traditional quantum key distribution systems employ similar probabilities for the different communication modes and thus reject at least half of the transmitted data. The invention substantially reduces the amount of discarded data (those that are encoded and decoded in different communication modes e.g. using different operators) in quantum key distribution without compromising security by using significantly different probabilities for the different communication modes. Data is separated into various sets according to the actual operators used in the encoding and decoding process and the error rate for each set is determined individually. The invention increases the key distribution rate of the BB84 key distribution scheme proposed by Bennett and Brassard in 1984. Using the invention, the key distribution rate increases with the number of quantum signals transmitted and can be doubled asymptotically. 23 figs.
Quantum Dot-Based Cell Motility Assay
Gu, Weiwei; Pellegrino, Teresa; Parak Wolfgang J; Boudreau,Rosanne; Le Gros, Mark A.; Gerion, Daniele; Alivisatos, A. Paul; Larabell, Carolyn A.
2005-06-06
Because of their favorable physical and photochemical properties, colloidal CdSe/ZnS-semiconductor nanocrystals (commonly known as quantum dots) have enormous potential for use in biological imaging. In this report, we present an assay that uses quantum dots as markers to quantify cell motility. Cells that are seeded onto a homogeneous layer of quantum dots engulf and absorb the nanocrystals and, as a consequence, leave behind a fluorescence-free trail. By subsequently determining the ratio of cell area to fluorescence-free track area, we show that it is possible to differentiate between invasive and noninvasive cancer cells. Because this assay uses simple fluorescence detection, requires no significant data processing, and can be used in live-cell studies, it has the potential to be a powerful new tool for discriminating between invasive and noninvasive cancer cell lines or for studying cell signaling events involved in migration.
Photovoltaic and thermophotovoltaic devices with quantum barriers
Wernsman, Bernard R. (Jefferson Hills, PA)
2007-04-10
A photovoltaic or thermophotovoltaic device includes a diode formed by p-type material and n-type material joined at a p-n junction and including a depletion region adjacent to said p-n junction, and a quantum barrier disposed near or in the depletion region of the p-n junction so as to decrease device reverse saturation current density while maintaining device short circuit current density. In one embodiment, the quantum barrier is disposed on the n-type material side of the p-n junction and decreases the reverse saturation current density due to electrons while in another, the barrier is disposed on the p-type material side of the p-n junction and decreases the reverse saturation current density due to holes. In another embodiment, both types of quantum barriers are used.
Theory Of Alkyl Terminated Silicon Quantum Dots
Reboredo, F; Galli, G
2004-08-19
We have carried out a series of ab-initio calculations to investigate changes in the optical properties of Si quantum dots as a function of surface passivation. In particular, we have compared hydrogen passivated dots with those having alkyl groups at the surface. We find that, while on clusters with reconstructed surfaces a complete alkyl passivation is possible, steric repulsion prevents full passivation of Si dots with unreconstructed surfaces. In addition, our calculations show that steric repulsion may have a dominant effect in determining the surface structure, and eventually the stability of alkyl passivated clusters, with results dependent on the length of the carbon chain. Alkyl passivation weakly affects optical gaps of silicon quantum dots, while it substantially decreases ionization potentials and electron affinities and affect their excited state properties. On the basis of our results we propose that alkyl terminated quantum dots may be size selected taking advantage of the change in ionization potential as a function of the cluster size.
Synthesis of Non-blinking Semiconductor Quantum Dots Emitting...
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37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 77 NANOSCIENCE AND NANOTECHNOLOGY; ALIGNMENT; CADMIUM; EMISSION SPECTRA; FLUORESCENCE; QUANTUM DOTS; RECOMBINATION;...
Signatures of quantum chaos in Wigner and Husimi representations
Lee, S.B.; Feit, M.D. (Physics Department, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States) Department of Applied Science, University of California, Davis/Livermore, Livermore, California 94550 (United States))
1993-06-01
In this paper, we study the quantum manifestations of classical chaos in phase space using Wigner and Husimi distribution functions. We test the claim that Husimi represents the correspondence better than Wigner does. The results show the claim is valid. We also use a quantum dissipation scheme empirically for classically damped motions often characterized by strange attractors. We believe quantum resemblance to classical distributions can be regarded as signatures of quantum chaos in phase space.
Identification of open quantum systems from observable time traces
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Zhang, Jun; Sarovar, Mohan
2015-05-27
Estimating the parameters that dictate the dynamics of a quantum system is an important task for quantum information processing and quantum metrology, as well as fundamental physics. In our paper we develop a method for parameter estimation for Markovian open quantum systems using a temporal record of measurements on the system. Furthermore, the method is based on system realization theory and is a generalization of our previous work on identification of Hamiltonian parameters.
Tampering detection system using quantum-mechanical systems
Humble, Travis S. (Knoxville, TN); Bennink, Ryan S. (Knoxville, TN); Grice, Warren P. (Oak Ridge, TN)
2011-12-13
The use of quantum-mechanically entangled photons for monitoring the integrity of a physical border or a communication link is described. The no-cloning principle of quantum information science is used as protection against an intruder's ability to spoof a sensor receiver using a `classical` intercept-resend attack. Correlated measurement outcomes from polarization-entangled photons are used to protect against quantum intercept-resend attacks, i.e., attacks using quantum teleportation.
Quantum-size-controlled photoelectrochemical etching of semiconductor
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nanostructures (Patent) | SciTech Connect Patent: Quantum-size-controlled photoelectrochemical etching of semiconductor nanostructures Citation Details In-Document Search Title: Quantum-size-controlled photoelectrochemical etching of semiconductor nanostructures Quantum-size-controlled photoelectrochemical (QSC-PEC) etching provides a new route to the precision fabrication of epitaxial semiconductor nanostructures in the sub-10-nm size regime. For example, quantum dots (QDs) can be
RKKY interaction in a chirally coupled double quantum dot system...
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Subject: 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CHIRALITY; EXCHANGE INTERACTIONS; KONDO EFFECT; MAGNETIC FIELDS; QUANTUM DOTS; TEMPERATURE DEPENDENCE ...
Fermentative Method for Making Nonoxide Fluorescent Nanoparticles (Quantum
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Dots) - Energy Innovation Portal Fermentative Method for Making Nonoxide Fluorescent Nanoparticles (Quantum Dots) Oak Ridge National Laboratory Contact ORNL About This Technology Incubation of quantum dots Incubation of quantum dots Technology Marketing SummaryA fermentative method for scalable, economical production of tailored quantum dots.DescriptionA method for manufacturing nanoparticles of certain nonoxide compounds of metals and nonmetals. The metals are typically Zn, Ag, Hg, Cd, Fe,
NREL and Partners Demonstrate Quantum Dots that Assemble Themselves - News
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Releases | NREL and Partners Demonstrate Quantum Dots that Assemble Themselves Surprising breakthrough could bolster quantum photonics, solar cell efficiency February 8, 2013 Scientists from the U.S. Department of Energy's National Renewable Energy Laboratory and other labs have demonstrated a process whereby quantum dots can self-assemble at optimal locations in nanowires, a breakthrough that could improve solar cells, quantum computing, and lighting devices. A paper on the new technology,
Quantum Well Thermoelectric Truck Air Conditioning | Department of Energy
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Thermoelectric Truck Air Conditioning Quantum Well Thermoelectric Truck Air Conditioning Discusses advantages of quantum-well TE cooler, including no moving parts, no gases, performance on par with conventional, and easy switching to heat pump mode PDF icon bass.pdf More Documents & Publications High-Efficiency Quantum-Well Thermoelectrics for Waste Heat Power Generation Fabrication of A Quantum Well Based System for Truck HVAC Recent Progress in the Development of High Efficiency
Maxwell-Garnett effective medium theory: Quantum nonlocal effects
Moradi, Afshin
2015-04-15
We develop the Maxwell-Garnett theory for the effective medium approximation of composite materials with metallic nanoparticles by taking into account the quantum spatial dispersion effects in dielectric response of nanoparticles. We derive a quantum nonlocal generalization of the standard Maxwell-Garnett formula, by means the linearized quantum hydrodynamic theory in conjunction with the Poisson equation as well as the appropriate additional quantum boundary conditions.
Universal entanglement entropy in two-dimensional conformal quantum
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critical points (Journal Article) | SciTech Connect Universal entanglement entropy in two-dimensional conformal quantum critical points Citation Details In-Document Search Title: Universal entanglement entropy in two-dimensional conformal quantum critical points We study the scaling behavior of the entanglement entropy of two-dimensional conformal quantum critical systems, i.e., systems with scale-invariant wave functions. They include two-dimensional generalized quantum dimer models on
Deformation Quantization: Quantum Mechanic Lives and Works in...
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DENSITY MATRIX; DISTRIBUTION FUNCTIONS; FERMILAB; HILBERT SPACE; NUCLEAR PHYSICS; OPTICS; PATH INTEGRALS; PHASE SPACE; PROCESSING; QUANTIZATION; QUANTUM MECHANICS; UNCERTAINTY...
Quantum stochastic thermodynamic on harmonic networks
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Deffner, Sebastian
2016-01-04
Fluctuation theorems are symmetry relations for the probability to observe an amount of entropy production in a finite-time process. In a recent paper Pigeon et al (2016 New. J. Phys. 18 013009) derived fluctuation theorems for harmonic networks by means of the large deviation theory. Furthermore, their novel approach is illustrated with various examples of experimentally relevant systems. As a main result, however, Pigeon et al provide new insight how to consistently formulate quantum stochastic thermodynamics, and provide new and robust tools for the study of the thermodynamics of quantum harmonic networks.
Bilayer graphene quantum dot defined by topgates
Müller, André; Kaestner, Bernd; Hohls, Frank; Weimann, Thomas; Pierz, Klaus; Schumacher, Hans W., E-mail: hans.w.schumacher@ptb.de [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany)
2014-06-21
We investigate the application of nanoscale topgates on exfoliated bilayer graphene to define quantum dot devices. At temperatures below 500 mK, the conductance underneath the grounded gates is suppressed, which we attribute to nearest neighbour hopping and strain-induced piezoelectric fields. The gate-layout can thus be used to define resistive regions by tuning into the corresponding temperature range. We use this method to define a quantum dot structure in bilayer graphene showing Coulomb blockade oscillations consistent with the gate layout.
High Temperature Quantum Well Materials | Department of Energy
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Quantum Well Materials High Temperature Quantum Well Materials Seebeck coefficients of >1,000 microvolt/degree C and resistivities of 1 milliohm-cm or less were obtained. PDF icon deer08_bass.pdf More Documents & Publications High Temperature Thermoelectric Materials Quantum Well Thermoelectrics and Waste Heat Recovery
Self-triggering superconducting fault current limiter
Yuan, Xing (Albany, NY); Tekletsadik, Kasegn (Rexford, NY)
2008-10-21
A modular and scaleable Matrix Fault Current Limiter (MFCL) that functions as a "variable impedance" device in an electric power network, using components made of superconducting and non-superconducting electrically conductive materials. The matrix fault current limiter comprises a fault current limiter module that includes a superconductor which is electrically coupled in parallel with a trigger coil, wherein the trigger coil is magnetically coupled to the superconductor. The current surge doing a fault within the electrical power network will cause the superconductor to transition to its resistive state and also generate a uniform magnetic field in the trigger coil and simultaneously limit the voltage developed across the superconductor. This results in fast and uniform quenching of the superconductors, significantly reduces the burnout risk associated with non-uniformity often existing within the volume of superconductor materials. The fault current limiter modules may be electrically coupled together to form various "n" (rows).times."m" (columns) matrix configurations.
Weak phase stiffness and nature of the quantum critical point in underdoped cuprates
Yildirim, Yucel; Ku, Wei
2015-11-02
We demonstrate that the zero-temperature superconducting phase diagram of underdoped cuprates can be quantitatively understood in the strong binding limit, using only the experimental spectral function of the â€śnormalâ€ť pseudogap phase without any free parameter. In the prototypical (La_{1â€“x}Sr_{x})_{2}CuO_{4}, a kinetics-driven d-wave superconductivity is obtained above the critical doping Î´_{c} ~ 5.2%, below which complete loss of superfluidity results from local quantum fluctuation involving local p-wave pairs. Near the critical doping, an enormous mass enhancement of the local pairs is found responsible for the observed rapid decrease of phase stiffness. Lastly, a striking mass divergence is predicted at Î´_{c} that dictates the occurrence of the observed quantum critical point and the abrupt suppression of the Nernst effects in the nearby region.
Final LDRD report : infrared detection and power generation using self-assembled quantum dots.
Cederberg, Jeffrey George; Ellis, Robert; Shaner, Eric Arthur
2008-02-01
Alternative solutions are desired for mid-wavelength and long-wavelength infrared radiation detection and imaging arrays. We have investigated quantum dot infrared photodetectors (QDIPs) as a possible solution for long-wavelength infrared (8 to 12 {mu}m) radiation sensing. This document provides a summary for work done under the LDRD 'Infrared Detection and Power Generation Using Self-Assembled Quantum Dots'. Under this LDRD, we have developed QDIP sensors and made efforts to improve these devices. While the sensors fabricated show good responsivity at 80 K, their detectivity is limited by high noise current. Following efforts concentrated on how to reduce or eliminate this problem, but with no clear path was identified to the desired performance improvements.
Birefringence in the transparency region of GaAs/AlAs multiple quantum wells
Sirenko, A.A.; Etchegoin, P.; Fainstein, A.; Eberl, K.; Cardona, M.
1999-09-01
Birefringence measurements for in-plane propagation of light below the absorption edge in GaAs/AlAs multiple quantum wells (MQW{close_quote}s) are reported for different well/barrier widths. A remarkable drop in the low-frequency limit of the birefringence has been observed for MQW structures with small periods and ascribed to the presence of local fields. The temperature dependence of the birefringence is also studied and complementary results in InP quantum dot structures are also presented. The latter exhibit a strong resonant birefringence, which can be explained by the reduced dimensionality in the joint density of states for optical transitions in the dots. {copyright} {ital 1999} {ital The American Physical Society}
Weak phase stiffness and nature of the quantum critical point in underdoped cuprates
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Yildirim, Yucel; Ku, Wei
2015-11-02
We demonstrate that the zero-temperature superconducting phase diagram of underdoped cuprates can be quantitatively understood in the strong binding limit, using only the experimental spectral function of the â€śnormalâ€ť pseudogap phase without any free parameter. In the prototypical (La1â€“xSrx)2CuO4, a kinetics-driven d-wave superconductivity is obtained above the critical doping Î´c ~ 5.2%, below which complete loss of superfluidity results from local quantum fluctuation involving local p-wave pairs. Near the critical doping, an enormous mass enhancement of the local pairs is found responsible for the observed rapid decrease of phase stiffness. Lastly, a striking mass divergence is predicted at Î´c thatmoreÂ Â» dictates the occurrence of the observed quantum critical point and the abrupt suppression of the Nernst effects in the nearby region.Â«Â less
Creation of Two-Particle Entanglement in Open Macroscopic Quantum Systems
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Merkli, M.; Berman, G. P.; Borgonovi, F.; Tsifrinovich, V. I.
2012-01-01
We consider an open quantum system of N not directly interacting spins (qubits) in contact with both local and collective thermal environments. The qubit-environment interactions are energy conserving. We trace out the variables of the thermal environments and N â’ 2 qubits to obtain the time-dependent reduced density matrix for two arbitrary qubits. We numerically simulate the reduced dynamics and the creation of entanglement (concurrence) as a function of the parameters of the thermal environments and the number of qubits, N . Our results demonstrate that the two-qubit entanglementmoreÂ Â»generally decreases as N increases. We show analytically that, in the limit N â†’ âž , no entanglement can be created. This indicates that collective thermal environments cannot create two-qubit entanglement when many qubits are located within a region of the size of the environment coherence length. We discuss possible relevance of our consideration to recent quantum information devices and biosystems.Â«Â less
Bound on quantum computation time: Quantum error correction in a critical environment
Novais, E.; Mucciolo, Eduardo R.; Baranger, Harold U.
2010-08-15
We obtain an upper bound on the time available for quantum computation for a given quantum computer and decohering environment with quantum error correction implemented. First, we derive an explicit quantum evolution operator for the logical qubits and show that it has the same form as that for the physical qubits but with a reduced coupling strength to the environment. Using this evolution operator, we find the trace distance between the real and ideal states of the logical qubits in two cases. For a super-Ohmic bath, the trace distance saturates, while for Ohmic or sub-Ohmic baths, there is a finite time before the trace distance exceeds a value set by the user.
FK-DLR properties of a quantum multi-type Bose-gas with a repulsive interaction
Suhov, Y.; Stuhl, I.
2014-08-01
The paper extends earlier results from Suhov and Kelbert [“FK-DLR states of a quantum Bose-gas with a hardcore interaction,” http://arxiv.org/abs/arXiv:1304.0782 ] and Suhov et al. [“Shift-invariance for FK-DLR states of a 2D quantum Bose-gas,” http://arxiv.org/abs/arXiv:1304.4177 ] about infinite-volume quantum bosonic states (FK-DLR states) to the case of multi-type particles with non-negative interactions. (An example is a quantum Widom–Rowlinson model.) Following the strategy from Suhov and Kelbert and Suhov et al., we establish that, for the values of fugacity z?(0, 1) and inverse temperature ? > 0, finite-volume Gibbs states form a compact family in the thermodynamic limit. Next, in dimension two we show that any limit-point state (an FK-DLR state in the terminology adopted in Suhov and Kelbert and Suhov et al.) is translation-invariant.
Slow phase relaxation as a route to quantum computing beyond the quantum chaos border
Flores, J.; Seligman, T.H. [Centro de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, Cuernavaca, Morelos (Mexico); Kun, S.Yu. [Centro de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, Cuernavaca, Morelos (Mexico); Centre for Nonlinear Physics, RSPhysSE, ANU, Canberra ACT 0200 (Australia); Department of Theoretical Physics, RSPhysSE, ANU, Canberra ACT 0200 (Australia)
2005-07-01
We reveal that phase memory can be much longer than energy relaxation in systems with exponentially large dimensions of Hilbert space; this finding is documented by 50 years of nuclear experiments, though the information is somewhat hidden. For quantum computers Hilbert spaces of dimension 2{sup 100} or larger will be typical and therefore this effect may contribute significantly to reduce the problems of scaling of quantum computers to a useful number of qubits.
Sandia Develops a Synthesis of Quantum Dots that Increases the Quantum
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Yield to 95.5% a Synthesis of Quantum Dots that Increases the Quantum Yield to 95.5% - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery
Synthesis of CdSe quantum dots for quantum dot sensitized solar cell
Singh, Neetu Kapoor, Avinashi; Kumar, Vinod; Mehra, R. M.
2014-04-24
CdSe Quantum Dots (QDs) of size 0.85 nm were synthesized using chemical route. ZnO based Quantum Dot Sensitized Solar Cell (QDSSC) was fabricated using CdSe QDs as sensitizer. The Pre-synthesized QDs were found to be successfully adsorbed on front ZnO electrode and had potential to replace organic dyes in Dye Sensitized Solar Cells (DSSCs). The efficiency of QDSSC was obtained to be 2.06 % at AM 1.5.
Exploring Classically Chaotic Potentials with a Matter Wave Quantum Probe
Gattobigio, G. L. [Laboratoire de Collisions Agregats Reactivite, CNRS UMR 5589, IRSAMC, Universite de Toulouse (UPS), 118 Route de Narbonne, 31062 Toulouse CEDEX 4 (France); Laboratoire Kastler Brossel, Ecole Normale Superieure, 24 rue Lhomond, 75005 Paris (France); Couvert, A. [Laboratoire Kastler Brossel, Ecole Normale Superieure, 24 rue Lhomond, 75005 Paris (France); Georgeot, B. [Laboratoire de Physique Theorique (IRSAMC), Universite de Toulouse (UPS), 31062 Toulouse (France); CNRS, LPT UMR5152 (IRSAMC), 31062 Toulouse (France); Guery-Odelin, D. [Laboratoire de Collisions Agregats Reactivite, CNRS UMR 5589, IRSAMC, Universite de Toulouse (UPS), 118 Route de Narbonne, 31062 Toulouse CEDEX 4 (France)
2011-12-16
We study an experimental setup in which a quantum probe, provided by a quasimonomode guided atom laser, interacts with a static localized attractive potential whose characteristic parameters are tunable. In this system, classical mechanics predicts a transition from regular to chaotic behavior as a result of the coupling between the different degrees of freedom. Our experimental results display a clear signature of this transition. On the basis of extensive numerical simulations, we discuss the quantum versus classical physics predictions in this context. This system opens new possibilities for investigating quantum scattering, provides a new testing ground for classical and quantum chaos, and enables us to revisit the quantum-classical correspondence.
Controlled quantum-state transfer in a spin chain
Gong, Jiangbin [Department of Physics and Center for Computational Science and Engineering, National University of Singapore, 117542 (Singapore); Brumer, Paul [Chemical Physics Theory Group and Center for Quantum Information and Quantum Control, University of Toronto, Toronto M5S 3H6 (Canada)
2007-03-15
Control of the transfer of quantum information encoded in quantum wave packets moving along a spin chain is demonstrated. Specifically, based on a relationship with control in a paradigm of quantum chaos, it is shown that wave packets with slow dispersion can automatically emerge from a class of initial superposition states involving only a few spins, and that arbitrary unspecified traveling wave packets can be nondestructively stopped and later relaunched with perfection. The results establish an interesting application of quantum chaos studies in quantum information science.
Driven Morse oscillator: Classical chaos, quantum theory, and photodissociation
Goggin, M.E.; Milonni, P.W.
1988-02-01
We compare the classical and quantum theories of a Morse oscillator driven by a sinusoidal field, focusing attention on multiple-photon excitation and dissociation. In both the classical and quantum theories the threshold field strength for dissociation may be estimated fairly accurately on the basis of classical resonance overlap, and the classical and quantum results for the threshold are in good agreement except near higher-order classical resonances and quantum multiphoton resonances. We discuss the possibility of ''quantum chaos'' in such driven molecular systems and use the Morse oscillator to test the manifestations of classical resonance overlap suggested semiclassically.
Ultrafast carrier capture in InGaAs quantum posts
Talbayev, Diyar; Taylor, Antoinette J; Stehr, D; Morris, C M; Wagner, M; Kim, H C; Schneider, H; Petroff, P M; Sherwin, M S
2009-01-01
To explore the capture dynamics of photoexcited carriers in semiconductor quantum posts, optical pump - THz probe and time-resolved photoluminescence spectroscopy were performed. The results of the THz experiment show that after ultrafast excitation, electrons relax within a few picoseconds into the quantum posts, which are acting as efficient traps. The saturation of the quantum post states, probed by photoluminescence, was reached approximately at ten times the quantum post density in the samples. The results imply that quantum posts are posts highly attractive nanostructures for future device applications.
COLLOQUIUM: Introduction to Quantum Algorithms | Princeton Plasma Physics
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Lab December 9, 2015, 4:15pm to 5:30pm MBG AUDITORIUM COLLOQUIUM: Introduction to Quantum Algorithms Dr. Nadya Shirokova University of Santa Clara Quantum computers are not an abstraction anymore - Google, NASA and USRA recently announced formation of the Quantum Artificial Intelligence Lab equipped with 1,000-qubit quantum computer. In this talk we will focus on quantum algorithms such as Deutsch, Shor's and Grover's and will discuss why they are faster than the classical ones. We will also
Selectivity in multiple quantum nuclear magnetic resonance
Warren, W.S.
1980-11-01
The observation of multiple-quantum nuclear magnetic resonance transitions in isotropic or anisotropic liquids is shown to give readily interpretable information on molecular configurations, rates of motional processes, and intramolecular interactions. However, the observed intensity of high multiple-quantum transitions falls off dramatically as the number of coupled spins increases. The theory of multiple-quantum NMR is developed through the density matrix formalism, and exact intensities are derived for several cases (isotropic first-order systems and anisotropic systems with high symmetry) to shown that this intensity decrease is expected if standard multiple-quantum pulse sequences are used. New pulse sequences are developed which excite coherences and produce population inversions only between selected states, even though other transitions are simultaneously resonant. One type of selective excitation presented only allows molecules to absorb and emit photons in groups of n. Coherent averaging theory is extended to describe these selective sequences, and to design sequences which are selective to arbitrarily high order in the Magnus expansion. This theory and computer calculations both show that extremely good selectivity and large signal enhancements are possible.
Nonlinear quantum electrodynamics in vacuum and plasmas
Brodin, Gert; Lundin, Joakim; Marklund, Mattias
2010-12-14
We consider high field physics due to quantum electrodynamics, in particular those that can be studied in the next generation of laser facilities. Effective field theories based on the Euler-Heisenberg Lagrangian are briefly reviewed, and examples involving plasma- and vacuum physics are given.
Adiabatic limits on Riemannian Heisenberg manifolds
Yakovlev, A A
2008-02-28
An asymptotic formula is obtained for the distribution function of the spectrum of the Laplace operator, in the adiabatic limit for the foliation defined by the orbits of an invariant flow on a compact Riemannian Heisenberg manifold. Bibliography: 21 titles.
A2Wind Limited | Open Energy Information
Startup with strong capability in carbon fibre design targeting the wind turbine blade space. References: A2Wind Limited1 This article is a stub. You can help OpenEI by...
Eclectic Energy Limited | Open Energy Information
Energy Limited Place: Nottinghamshire, United Kingdom Zip: NG21 9PR Sector: Wind energy Product: Design, manufacture D400, StealthGen micro wind, DuoGen wind and water...
Greenrock Energy Services Limited | Open Energy Information
Kingdom Zip: EH2 2JG Product: Scotland-based company installing ground source heat pump systems. References: Greenrock Energy Services Limited1 This article is a stub. You...
EarthEnergy Limited | Open Energy Information
Cornwall, United Kingdom Product: EarthEnergy Systems specialises in ground source heat pump systems. References: EarthEnergy Limited1 This article is a stub. You can help OpenEI...
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Principle Energy Limited Place: Isle of Man, United Kingdom Zip: 1M1 1LB Sector: Renewable Energy Product: A UK-based renewable energy company focusing on bioethanol projects in...
Crionaig Power Limited | Open Energy Information
government approval for a 140MW, 39-turbine wind farm at Eisgein on the Isle of Lewis. References: Crionaig Power Limited1 This article is a stub. You can help OpenEI by...
Defining engine efficiency limits | Department of Energy
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
engine efficiency limits Defining engine efficiency limits Investigates the potential to reduce engine efficiency losses and how this impacts the entire system in terms of a direct increase in work output or a change in the loss mechanism. PDF icon deer11_edwards.pdf More Documents & Publications High Efficiency Engine Systems Development and Evaluation Identification and Evaluation of Near-term Opportunities for Efficiency Improvement High Efficiency Engine Systems Development and
De Roeck, W. E-mail: christian.maes@fys.kuleuven.be E-mail: marius.schutz@fys.kuleuven.be; Maes, C. E-mail: christian.maes@fys.kuleuven.be E-mail: marius.schutz@fys.kuleuven.be; Schütz, M. E-mail: christian.maes@fys.kuleuven.be E-mail: marius.schutz@fys.kuleuven.be; Neto?ný, K. E-mail: christian.maes@fys.kuleuven.be E-mail: marius.schutz@fys.kuleuven.be
2015-02-15
We study the projection on classical spins starting from quantum equilibria. We show Gibbsianness or quasi-locality of the resulting classical spin system for a class of gapped quantum systems at low temperatures including quantum ground states. A consequence of Gibbsianness is the validity of a large deviation principle in the quantum system which is known and here recovered in regimes of high temperature or for thermal states in one dimension. On the other hand, we give an example of a quantum ground state with strong nonlocality in the classical restriction, giving rise to what we call measurement induced entanglement and still satisfying a large deviation principle.
Non-abelian fractional quantum hall effect for fault-resistant topological
Office of Scientific and Technical Information (OSTI)
quantum computation. (Technical Report) | SciTech Connect Technical Report: Non-abelian fractional quantum hall effect for fault-resistant topological quantum computation. Citation Details In-Document Search Title: Non-abelian fractional quantum hall effect for fault-resistant topological quantum computation. Topological quantum computation (TQC) has emerged as one of the most promising approaches to quantum computation. Under this approach, the topological properties of a non-Abelian
Fine, Dana S.; Sawin, Stephen
2014-06-15
Following Feynman's prescription for constructing a path integral representation of the propagator of a quantum theory, a short-time approximation to the propagator for imaginary-time, N = 1 supersymmetric quantum mechanics on a compact, even-dimensional Riemannian manifold is constructed. The path integral is interpreted as the limit of products, determined by a partition of a finite time interval, of this approximate propagator. The limit under refinements of the partition is shown to converge uniformly to the heat kernel for the Laplace-de Rham operator on forms. A version of the steepest descent approximation to the path integral is obtained, and shown to give the expected short-time behavior of the supertrace of the heat kernel.
Remote Chemical Sensing Using Quantum Cascade Lasers
Harper, Warren W.; Strasburg, Jana D.; Aker, Pam M.; Schultz, John F.
2004-01-20
Research done by the IR sensors team at PNNL is focused on developing advanced spectroscopic methods for detecting signatures of nuclear, chemical, biological and explosives weapons or weapons production. The sensors we develop fall into two categories: remote sensors that can be operated at distances ranging from 150 m to 10 km, and point sensors that are used for in-situ inspection and detection. FY03 has seen an explosion in FM DIAL progress with the net result being solid confirmation that FM DIAL is a technique capable of remote chemical monitoring in a wide variety of venues. For example, FM DIAL was used to detect a small plume of hydrogen sulfide, a candidate CW agent, released in the desert environment of the Hanford 200 Area site. These experiments were conducted over a range of physical conditions including outside temperatures ranging from 70 F to 105 F and turbulence conditions ranging from quiescent to chaotic. We are now rapidly developing the information needed to design prototype FM DIAL systems that are optimized for specific applications that include scenarios such as fixed position stand-off detection and mobile UAV mounted remote monitoring. Just as an example, in FY04 we will use FM DIAL to detect both in-facility and outdoor release of enriched UF6. The rapid progress in FM DIAL research made in FY03 is attributed to several advances. First, final construction of a custom-designed trailer allowed the instrument to be housed in a mobile temperature-controlled environment. This allowed the experiment to be transported to several locations so that data could be collected under a range of physical conditions. This has led to a better understanding of a variety of experimental noise sources. With this knowledge, we have been able to implement several changes in the way the FM DIAL data is collected and processed, with the net result being a drastic improvement in our confidence of analyte concentration measurement and an improvement i n the instrument detection limit. The range of chemicals detectable by FM DIAL has also been extended. Prior to FY03 only water and nitrous oxide (N2O) had been seen. Experiments on extending the tuning range of the quantum cascade laser (QCL) currently used in the experiments demonstrate that many more species are now accessible including H2S, C2F4H2, and CH4. We additionally demonstrated that FM DIAL measurements can be made using short wave infrared (SWIR) telecommunications lasers. While measurements made using these components are noisier because turbulence and particulate matter cause more interference in this spectral region, monitoring in this region enables larger species to be detected simply because these lasers have a greater tuning range. In addition, SWIR monitoring also allows for the detection of second-row hydride species such as HF and HCl, which are important nuclear and CWA proliferation signatures.
A brightness exceeding simulated Langmuir limit
Nakasuji, Mamoru
2013-08-15
When an excitation of the first lens determines a beam is parallel beam, a brightness that is 100 times higher than Langmuir limit is measured experimentally, where Langmuir limits are estimated using a simulated axial cathode current density which is simulated based on a measured emission current. The measured brightness is comparable to Langmuir limit, when the lens excitation is such that an image position is slightly shorter than a lens position. Previously measured values of brightness for cathode apical radii of curvature 20, 60, 120, 240, and 480 ?m were 8.7, 5.3, 3.3, 2.4, and 3.9 times higher than their corresponding Langmuir limits, respectively, in this experiment, the lens excitation was such that the lens and the image positions were 180 mm and 400 mm, respectively. From these measured brightness for three different lens excitation conditions, it is concluded that the brightness depends on the first lens excitation. For the electron gun operated in a space charge limited condition, some of the electrons emitted from the cathode are returned to the cathode without having crossed a virtual cathode. Therefore, method that assumes a Langmuir limit defining method using a Maxwellian distribution of electron velocities may need to be revised. For the condition in which the values of the exceeding the Langmuir limit are measured, the simulated trajectories of electrons that are emitted from the cathode do not cross the optical axis at the crossover, thus the law of sines may not be valid for high brightness electron beam systems.
Defining coiled tubing limits -- A new approach
Newman, K.R.; Sathuvalli, U.B.; Stone, L.R.; Wolhart, S.
1996-12-31
The burst, collapse and axial load operating limits for Coiled Tubing (CT) are currently established using the Von Mises incipient yield criterion. This criterion has historically been used to calculate the limits for oil country tubular goods (OCTG). The limits according to this criterion are based on the point at which the pipe material reaches a load state in which it begins to yield. Because of the bending that occurs when the CT is spooled on and off the reel, and when it is bent over the guide arch, the CT is already far beyond the yield point before it enters a well. Thus, this criterion does not really apply to CT. This paper describes a research project currently in progress. The purpose of this project is to define a new set of CT limits based on criteria other than incipient yield. This new approach to setting CT operating limits takes into account the internal residual stresses in the CT which are a consequence of repeated bending cycles and the accompanying change in material properties.
Goryachev, Maxim Ivanov, Eugene N.; Tobar, Michael E.; Kann, Frank van; Galliou, Serge
2014-10-13
Thermal Nyquist noise fluctuations of high-Q bulk acoustic wave cavities have been observed at cryogenic temperatures with a DC superconducting quantum interference device amplifier. High Q modes with bandwidths of few tens of milliHz produce thermal fluctuations with a signal-to-noise ratio of up to 23?dB. The estimated effective temperature from the Nyquist noise is in good agreement with the physical temperature of the device, confirming the validity of the equivalent circuit model and the non-existence of any excess resonator self-noise. The measurements also confirm that the quality factor remains extremely high (Q?>?10{sup 8} at low order overtones) for very weak (thermal) system motion at low temperatures, when compared to values measured with relatively strong external excitation. This result represents an enabling step towards operating such a high-Q acoustic device at the standard quantum limit.
Bilinear covariants and spinor fields duality in quantum Clifford algebras
Ab?amowicz, Rafa?; Gonçalves, Icaro; Rocha, Roldăo da
2014-10-15
Classification of quantum spinor fields according to quantum bilinear covariants is introduced in a context of quantum Clifford algebras on Minkowski spacetime. Once the bilinear covariants are expressed in terms of algebraic spinor fields, the duality between spinor and quantum spinor fields can be discussed. Thus, by endowing the underlying spacetime with an arbitrary bilinear form with an antisymmetric part in addition to a symmetric spacetime metric, quantum algebraic spinor fields and deformed bilinear covariants can be constructed. They are thus compared to the classical (non quantum) ones. Classes of quantum spinor fields classes are introduced and compared with Lounesto's spinor field classification. A physical interpretation of the deformed parts and the underlying Z-grading is proposed. The existence of an arbitrary bilinear form endowing the spacetime already has been explored in the literature in the context of quantum gravity [S. W. Hawking, “The unpredictability of quantum gravity,” Commun. Math. Phys. 87, 395 (1982)]. Here, it is shown further to play a prominent role in the structure of Dirac, Weyl, and Majorana spinor fields, besides the most general flagpoles and flag-dipoles. We introduce a new duality between the standard and the quantum spinor fields, by showing that when Clifford algebras over vector spaces endowed with an arbitrary bilinear form are taken into account, a mixture among the classes does occur. Consequently, novel features regarding the spinor fields can be derived.
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PP-206 Frontera Generation Limited Partnership | Department of...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
PP-206 Frontera Generation Limited Partnership PP-206 Frontera Generation Limited Partnership Presidential permit authorizing Frontera Generation Limited Partnership to construct,...
Multiple soft limits of cosmological correlation functions
Joyce, Austin; Khoury, Justin; Simonovi?, Marko E-mail: jkhoury@sas.upenn.edu
2015-01-01
We derive novel identities satisfied by inflationary correlation functions in the limit where two external momenta are taken to be small. We derive these statements in two ways: using background-wave arguments and as Ward identities following from the fixed-time path integral. Interestingly, these identities allow us to constrain some of the O(q{sup 2}) components of the soft limit, in contrast to their single-soft analogues. We provide several nontrivial checks of our identities both in the context of resonant non-Gaussianities and in small sound speed models. Additionally, we extend the relation at lowest order in external momenta to arbitrarily many soft legs, and comment on the many-soft extension at higher orders in the soft momentum. Finally, we consider how higher soft limits lead to identities satisfied by correlation functions in large-scale structure.
ON COMPUTING UPPER LIMITS TO SOURCE INTENSITIES
Kashyap, Vinay L.; Siemiginowska, Aneta [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Van Dyk, David A.; Xu Jin [Department of Statistics, University of California, Irvine, CA 92697-1250 (United States); Connors, Alanna [Eureka Scientific, 2452 Delmer Street, Suite 100, Oakland, CA 94602-3017 (United States); Freeman, Peter E. [Department of Statistics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Zezas, Andreas, E-mail: vkashyap@cfa.harvard.ed, E-mail: asiemiginowska@cfa.harvard.ed, E-mail: dvd@ics.uci.ed, E-mail: jinx@ics.uci.ed, E-mail: aconnors@eurekabayes.co, E-mail: pfreeman@cmu.ed, E-mail: azezas@cfa.harvard.ed [Physics Department, University of Crete, P.O. Box 2208, GR-710 03, Heraklion, Crete (Greece)
2010-08-10
A common problem in astrophysics is determining how bright a source could be and still not be detected in an observation. Despite the simplicity with which the problem can be stated, the solution involves complicated statistical issues that require careful analysis. In contrast to the more familiar confidence bound, this concept has never been formally analyzed, leading to a great variety of often ad hoc solutions. Here we formulate and describe the problem in a self-consistent manner. Detection significance is usually defined by the acceptable proportion of false positives (background fluctuations that are claimed as detections, or Type I error), and we invoke the complementary concept of false negatives (real sources that go undetected, or Type II error), based on the statistical power of a test, to compute an upper limit to the detectable source intensity. To determine the minimum intensity that a source must have for it to be detected, we first define a detection threshold and then compute the probabilities of detecting sources of various intensities at the given threshold. The intensity that corresponds to the specified Type II error probability defines that minimum intensity and is identified as the upper limit. Thus, an upper limit is a characteristic of the detection procedure rather than the strength of any particular source. It should not be confused with confidence intervals or other estimates of source intensity. This is particularly important given the large number of catalogs that are being generated from increasingly sensitive surveys. We discuss, with examples, the differences between these upper limits and confidence bounds. Both measures are useful quantities that should be reported in order to extract the most science from catalogs, though they answer different statistical questions: an upper bound describes an inference range on the source intensity, while an upper limit calibrates the detection process. We provide a recipe for computing upper limits that applies to all detection algorithms.
Limited Conditions of Operations Tracking Program
Energy Science and Technology Software Center (OSTI)
1999-12-17
The Lco tracking program is a computer based solution for tracking time limited action items for Limited Conditions of Operation (LCO) for nuclear and industrial processes. This use is not limited to any process except those not requiring specific action steps and times. The visual and audible assistance the LCO Tracking Program provides significantly reduces the chance of missing crucial actions required for safe operation of any facility in time of limited operations. The LCOmoreÂ Â» Tracking Program maintains all applicable action steps and times for each limited condition for the facility in its data base. The LCO Tracking Program is used to enter that condition by number, and the data base provides the applicble action steps and starts tracking their times based on the time the LCO was entered. The LCO display graphically displays, by colored bar charts, the time expired/time remaining of each specific action item. At 60% time expired, the bar chart turns yellow to caution personnel and then turns red at 90% time expired. Then an audible alarm is sounded at 95% as a warning, to finish or accomplish the required actions to satisfy the requirements. These warning and alarm limits are modifiable by the user and can be set at different values for each action. The display file is dynamic in function, checking every minute, and responds in real time to changes to the LCO Tracking Form file, providing the visual and audible warnings as to the status of the action steps chosen for display. The LCO Tracking Program efficiently tracks action times in minutes or days, up to 2 years. All current LCO''s are easily documentated using the LCO Tracking Form file with ease of printing and disposition. The Lco Tracking Program is designed as a user friendly program with navigational buttons to simplify use.Â«Â less
Multichannel Pseudogap Kondo Model: Large-N Solution and Quantum-Critical Dynamics
Vojta, Matthias
2001-08-27
We discuss a multichannel SU(N) Kondo model which displays nontrivial zero-temperature phase transitions due to a conduction electron density of states vanishing with a power law at the Fermi level. In a particular large-N limit, the system is described by coupled integral equations corresponding to a dynamic saddle point. We exactly determine the universal low-energy behavior of spectral densities at the scale-invariant fixed points, obtain anomalous exponents, and compute scaling functions describing the crossover near the quantum-critical points. We argue that our findings are relevant to recent experiments on impurity-doped d -wave superconductors.
Photoluminescence studies of individual and few GaSb/GaAs quantum rings
Young, M. P.; Woodhead, C. S.; Roberts, J.; Noori, Y. J.; Noble, M. T.; Krier, A.; Hayne, M.; Young, R. J.; Smakman, E. P.; Koenraad, P. M.
2014-11-15
We present optical studies of individual and few GaSb quantum rings embedded in a GaAs matrix. Contrary to expectation for type-II confinement, we measure rich spectra containing sharp lines. These lines originate from excitonic recombination and are observed to have resolution-limited full-width at half maximum of 200 ?eV. The detail provided by these measurements allows the characteristic type-II blueshift, observed with increasing excitation power, to be studied at the level of individual nanostructures. These findings are in agreement with hole-charging being the origin of the observed blueshift.
Georgiou, C.; Leontiou, T.; Kelires, P. C.
2014-07-15
Atomistic Monte Carlo simulations, coupling thermodynamic and kinetic effects, resolve a longstanding controversy regarding the origin of composition profiles in heteroepitaxial SiGe quantum dots. It is shown that profiles with cores rich in the unstrained (Si) component derive from near-equilibrium processes and intraisland diffusion. Profiles with cores rich in the strained (Ge) component are of nonequilibrium nature, i.e., they are strain driven but kinetically limited. They are shaped by the distribution of kinetic barriers of atomic diffusion in the islands. The diffusion pathways are clearly revealed for the first time. Geometrical kinetics play a minor role.
Cosmin Obreja, Alexandru; Cristea, Dana; Radoi, Antonio; Gavrila, Raluca; Comanescu, Florin; Kusko, Cristian; Mihalache, Iuliana
2014-08-25
We show that graphene quantum dots (GQD) embedded in a semiconducting poly(3-hexylthiophene) polymeric matrix act as charge trapping nanomaterials. In plane current-voltage (I-V) measurements of thin films realized from this nanocomposite deposited on gold interdigitated electrodes revealed that the GQD enhanced dramatically the hole transport. I-V characteristics exhibited a strong nonlinear behavior and a pinched hysteresis loop, a signature of a memristive response. The transport properties of this nanocomposite were explained in terms of a trap controlled space charge limited current mechanism.
Feedback cooling of cantilever motion using a quantum point contact transducer
Montinaro, M.; Mehlin, A.; Solanki, H. S.; Peddibhotla, P.; Poggio, M.; Mack, S.; Awschalom, D. D.
2012-09-24
We use a quantum point contact (QPC) as a displacement transducer to measure and control the low-temperature thermal motion of a nearby micromechanical cantilever. The QPC is included in an active feedback loop designed to cool the cantilever's fundamental mechanical mode, achieving a squashing of the QPC noise at high gain. The minimum achieved effective mode temperature of 0.2 K and the displacement resolution of 10{sup -11} m/{radical}(Hz) are limited by the performance of the QPC as a one-dimensional conductor and by the cantilever-QPC capacitive coupling.
Quantum key distribution for 10 Gb/s dense wavelength division multiplexing networks
Patel, K. A.; Dynes, J. F.; Lucamarini, M.; Choi, I.; Sharpe, A. W.; Yuan, Z. L. Shields, A. J.; Penty, R. V.
2014-02-03
We demonstrate quantum key distribution (QKD) with bidirectional 10 Gb/s classical data channels in a single fiber using dense wavelength division multiplexing. Record secure key rates of 2.38 Mbps and fiber distances up to 70?km are achieved. Data channels are simultaneously monitored for error-free operation. The robustness of QKD is further demonstrated with a secure key rate of 445 kbps over 25?km, obtained in the presence of data lasers launching conventional 0 dBm power. We discuss the fundamental limit for the QKD performance in the multiplexing environment.
How state preparation can affect a quantum experiment: Quantum process tomography for open systems
Kuah, Aik-meng; Modi, Kavan; Rodriguez-Rosario, Cesar A.; Sudarshan, E. C. G. [Center for Complex Quantum Systems, University of Texas at Austin, Austin, Texas 78712 (United States)
2007-10-15
We study the effects of the preparation of input states in a quantum tomography experiment. We show that maps arising from a quantum process tomography experiment (called process maps) differ from the well-known dynamical maps. The difference between the two is due to the preparation procedure that is necessary for any quantum experiment. We study two preparation procedures: stochastic preparation and preparation by measurements. The stochastic preparation procedure yields process maps that are linear, while the preparations using von Neumann measurements lead to nonlinear processes and can only be consistently described by a bilinear process map. A process tomography recipe is derived for preparation by measurement for qubits. The difference between the two methods is analyzed in terms of a quantum process tomography experiment. A verification protocol is proposed to differentiate between linear processes and bilinear processes. We also emphasize that the preparation procedure will have a nontrivial effect for any quantum experiment in which the system of interest interacts with its environment.
From Entropic Dynamics to Quantum Theory
Caticha, Ariel
2009-12-08
Non-relativistic quantum theory is derived from information codified into an appropriate statistical model. The basic assumption is that there is an irreducible uncertainty in the location of particles so that the configuration space is a statistical manifold. The dynamics then follows from a principle of inference, the method of Maximum Entropy. The concept of time is introduced as a convenient way to keep track of change. The resulting theory resembles both Nelson's stochastic mechanics and general relativity. The statistical manifold is a dynamical entity: its geometry determines the evolution of the probability distribution which, in its turn, reacts back and determines the evolution of the geometry. There is a new quantum version of the equivalence principle: 'osmotic' mass equals inertial mass. Mass and the phase of the wave function are explained as features of purely statistical origin.
Electron states in semiconductor quantum dots
Dhayal, Suman S.; Ramaniah, Lavanya M.; Ruda, Harry E.; Nair, Selvakumar V.
2014-11-28
In this work, the electronic structures of quantum dots (QDs) of nine direct band gap semiconductor materials belonging to the group II-VI and III-V families are investigated, within the empirical tight-binding framework, in the effective bond orbital model. This methodology is shown to accurately describe these systems, yielding, at the same time, qualitative insights into their electronic properties. Various features of the bulk band structure such as band-gaps, band curvature, and band widths around symmetry points affect the quantum confinement of electrons and holes. These effects are identified and quantified. A comparison with experimental data yields good agreement with the calculations. These theoretical results would help quantify the optical response of QDs of these materials and provide useful input for applications.
Trace anomaly on a quantum spacetime manifold
Spallucci, Euro; Smailagic, Anais; Nicolini, Piero
2006-04-15
In this paper we investigate the trace anomaly in a space-time where single events are delocalized as a consequence of short distance quantum coordinate fluctuations. We obtain a modified form of heat kernel asymptotic expansion which does not suffer from short distance divergences. Calculation of the trace anomaly is performed using an IR regulator in order to circumvent the absence of UV infinities. The explicit form of the trace anomaly is presented and the corresponding 2D Polyakov effective action and energy-momentum tensor are obtained. The vacuum expectation value of the energy-momentum tensor in the Boulware, Hartle-Hawking and Unruh vacua is explicitly calculated in a rt section of a recently found, noncommutative inspired, Schwarzschild-like solution of the Einstein equations. The standard short distance divergences in the vacuum expectation values are regularized in agreement with the absence of UV infinities removed by quantum coordinate fluctuations.
Energy concentration in composite quantum systems
Kurcz, Andreas; Beige, Almut; Capolupo, Antonio; Vitiello, Giuseppe; Del Giudice, Emilio
2010-06-15
The spontaneous emission of photons from optical cavities and from trapped atoms has been studied extensively in the framework of quantum optics. Theoretical predictions based on the rotating wave approximation (RWA) are, in general, in very good agreement with experimental findings. However, current experiments aim at combining better and better cavities with large numbers of tightly confined atoms. Here we predict an energy concentrating mechanism in the behavior of such a composite quantum system which cannot be described by the RWA. Its result is the continuous leakage of photons through the cavity mirrors, even in the absence of external driving. We conclude with a discussion of the predicted phenomenon in the context of thermodynamics.
Quantum chaos in compact lattice QED
Berg, B.A. [Department of Physics, The Florida State University, Tallahassee, Florida 32306 (United States)] [Department of Physics, The Florida State University, Tallahassee, Florida 32306 (United States); [Supercomputer Computations Research Institute, The Florida State University, Tallahassee, Florida 32306 (United States); Markum, H. [Institut fuer Kernphysik, Technische Universitaet Wien, A-1040 Vienna (Austria)] [Institut fuer Kernphysik, Technische Universitaet Wien, A-1040 Vienna (Austria); Pullirsch, R. [Department of Physics, The Florida State University, Tallahassee, Florida 32306 (United States)] [Department of Physics, The Florida State University, Tallahassee, Florida 32306 (United States); [Institut fuer Kernphysik, Technische Universitaet Wien, A-1040 Vienna (Austria)
1999-05-01
Complete eigenvalue spectra of the staggered Dirac operator in quenched 4D compact QED are studied on 8{sup 3}{times}4 and 8{sup 3}{times}6 lattices. We investigate the behavior of the nearest-neighbor spacing distribution P(s) as a measure of the fluctuation properties of the eigenvalues in the strong coupling and the Coulomb phase. In both phases we find agreement with the Wigner surmise of the unitary ensemble of random-matrix theory indicating quantum chaos. Combining this with previous results on QCD, we conjecture that quite generally the non-linear couplings of quantum field theories lead to a chaotic behavior of the eigenvalues of the Dirac operator. {copyright} {ital 1999} {ital The American Physical Society}
Values and the quantum conception of man
Stapp, H.P.
1995-06-01
Classical mechanics is based upon a mechanical picture of nature that is fundamentally incorrect. It has been replaced at the basic level by a radically different theory: quantum mechanics. This change entails an enormous shift in one`s basic conception of nature, one that can profoundly alter the scientific image of man himself. Self-image is the foundation of values, and the replacement of the mechanistic self-image derived from classical mechanics by one concordant with quantum mechanics may provide the foundation of a moral order better suited to today`s times, a self-image that endows human life with meaning, responsibility, and a deeper linkage to nature as a whole.
Quantum Monte Carlo by message passing
Bonca, J.; Gubernatis, J.E.
1993-01-01
We summarize results of quantum Monte Carlo simulations of the degenerate single-impurity Anderson model using the impurity algorithm of Hirsch and Fye. Using methods of Bayesian statistical inference, coupled with the principle of maximum entropy, we extracted the single-particle spectral density from the imaginary-time Green's function. The variations of resulting spectral densities with model parameters agree qualitatively with the spectral densities predicted by NCA calculations. All the simulations were performed on a cluster of 16 IBM R6000/560 workstations under the control of the message-passing software PVM. We described the trivial parallelization of our quantum Monte Carlo code both for the cluster and the CM-5 computer. Other issues for effective parallelization of the impurity algorithm are also discussed.
Quantum Monte Carlo by message passing
Bonca, J.; Gubernatis, J.E.
1993-05-01
We summarize results of quantum Monte Carlo simulations of the degenerate single-impurity Anderson model using the impurity algorithm of Hirsch and Fye. Using methods of Bayesian statistical inference, coupled with the principle of maximum entropy, we extracted the single-particle spectral density from the imaginary-time Green`s function. The variations of resulting spectral densities with model parameters agree qualitatively with the spectral densities predicted by NCA calculations. All the simulations were performed on a cluster of 16 IBM R6000/560 workstations under the control of the message-passing software PVM. We described the trivial parallelization of our quantum Monte Carlo code both for the cluster and the CM-5 computer. Other issues for effective parallelization of the impurity algorithm are also discussed.
Geometric spin manipulation in semiconductor quantum dots
Prabhakar, Sanjay Melnik, Roderick; Inomata, Akira
2014-04-07
We propose a method to flip the spin completely by an adiabatic transport of quantum dots. We show that it is possible to flip the spin by inducing a geometric phase on the spin state of a quantum dot. We estimate the geometric spin flip time (approximately 2 ps) which turned out to be much shorter than the experimentally reported decoherence time (approximately 100 ns) that would provide an alternative means of fliping the spin before reaching decoherence. It is important that both the Rashba coupling and the Dresselhaus coupling are present for inducing a phase necessary for spin flip. If one of them is absent, the induced phase is trivial and irrelevant for spin-flip.
Process tomography for unitary quantum channels
Gutoski, Gus; Johnston, Nathaniel
2014-03-15
We study the number of measurements required for quantum process tomography under prior information, such as a promise that the unknown channel is unitary. We introduce the notion of an interactive observable and we show that any unitary channel acting on a d-level quantum system can be uniquely identified among all other channels (unitary or otherwise) with only O(d{sup 2}) interactive observables, as opposed to the O(d{sup 4}) required for tomography of arbitrary channels. This result generalizes to the problem of identifying channels with at most q Kraus operators, and slight improvements can be obtained if we wish to identify such a channel only among unital channels or among other channels with q Kraus operators. These results are proven via explicit construction of large subspaces of Hermitian matrices with various conditions on rank, eigenvalues, and partial trace. Our constructions are built upon various forms of totally nonsingular matrices.
Group representations, error bases and quantum codes
Knill, E
1996-01-01
This report continues the discussion of unitary error bases and quantum codes. Nice error bases are characterized in terms of the existence of certain characters in a group. A general construction for error bases which are non-abelian over the center is given. The method for obtaining codes due to Calderbank et al. is generalized and expressed purely in representation theoretic terms. The significance of the inertia subgroup both for constructing codes and obtaining the set of transversally implementable operations is demonstrated.
Quantum chaos and sensitivity to system parameters
Bhanot, G.V. (Institute for Advanced Study, Princeton, NJ (United States)); Parikh, J.C.; Sheorey, V.B. (Physical Research Lab., Navrangpura (India)); Pandey, A. (Jawaharlal Nehru Univ., New Delhi (India) Univ. of Rochester, NY (United States))
1990-01-01
The authors study the eigenfunctions and eigenvalues of the Hamiltonian H=p[sup 2][sub x]+p[sup 2][sub y]+x[sup 4]+y[sup 4]+[alpha]x[sup 2]y[sup 2] in the classically chaotic regime. It is shown that the overlap of wavefunctions at neighboring [alpha] values provides a sensitive measure to demonstrate the onset of chaos in quantum systems.
Second Generation Fractional Quantum Hall Effect
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Generation Fractional Quantum Hall Effect - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Fuel Cycle Defense Waste Management
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing?
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Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Rotaxanes are mechanically interlocked molecular architectures consisting of a dumbbell-shaped molecule, the "axle," that threads through a ring called a macrocycle. Because the rings can spin around and slide along the axle, rotaxanes are promising components of molecular machines. While most rotaxanes have been entirely organic, the physical properties desirable in molecular machines are mostly found in inorganic
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing?
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Rotaxanes are mechanically interlocked molecular architectures consisting of a dumbbell-shaped molecule, the "axle," that threads through a ring called a macrocycle. Because the rings can spin around and slide along the axle, rotaxanes are promising components of molecular machines. While most rotaxanes have been entirely organic, the physical properties desirable in molecular machines are mostly found in inorganic
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing?
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Rotaxanes are mechanically interlocked molecular architectures consisting of a dumbbell-shaped molecule, the "axle," that threads through a ring called a macrocycle. Because the rings can spin around and slide along the axle, rotaxanes are promising components of molecular machines. While most rotaxanes have been entirely organic, the physical properties desirable in molecular machines are mostly found in inorganic
Research Challenge 2: Quantum Dots and Phosphors
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2: Quantum Dots and Phosphors - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Fuel Cycle Defense Waste Management Programs
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing?
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Rotaxanes are mechanically interlocked molecular architectures consisting of a dumbbell-shaped molecule, the "axle," that threads through a ring called a macrocycle. Because the rings can spin around and slide along the axle, rotaxanes are promising components of molecular machines. While most rotaxanes have been entirely organic, the physical properties desirable in molecular machines are mostly found in inorganic
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing?
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Rotaxanes are mechanically interlocked molecular architectures consisting of a dumbbell-shaped molecule, the "axle," that threads through a ring called a macrocycle. Because the rings can spin around and slide along the axle, rotaxanes are promising components of molecular machines. While most rotaxanes have been entirely organic, the physical properties desirable in molecular machines are mostly found in inorganic
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing?
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Rotaxanes are mechanically interlocked molecular architectures consisting of a dumbbell-shaped molecule, the "axle," that threads through a ring called a macrocycle. Because the rings can spin around and slide along the axle, rotaxanes are promising components of molecular machines. While most rotaxanes have been entirely organic, the physical properties desirable in molecular machines are mostly found in inorganic
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing?
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Rotaxanes are mechanically interlocked molecular architectures consisting of a dumbbell-shaped molecule, the "axle," that threads through a ring called a macrocycle. Because the rings can spin around and slide along the axle, rotaxanes are promising components of molecular machines. While most rotaxanes have been entirely organic, the physical properties desirable in molecular machines are mostly found in inorganic
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing?
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Hybrid Rotaxanes: Interlocked Structures for Quantum Computing? Print Rotaxanes are mechanically interlocked molecular architectures consisting of a dumbbell-shaped molecule, the "axle," that threads through a ring called a macrocycle. Because the rings can spin around and slide along the axle, rotaxanes are promising components of molecular machines. While most rotaxanes have been entirely organic, the physical properties desirable in molecular machines are mostly found in inorganic
Analysis of Nuclear Quantum Phase Transitions
Li, Z. P.; Meng, J.; Niksic, T.; Vretenar, D.; Lalazissis, G. A.; Ring, P.
2009-08-26
A microscopic analysis, based on nuclear energy density functionals, is presented for shape phase transitions in Nd isotopes. Low-lying excitation spectra and transition probabilities are calculated starting from a five-dimensional Hamiltonian, with parameters determined by constrained relativistic mean-field calculations for triaxial shapes. The results reproduce available data, and show that there is an abrupt change of structure at N = 90, that corresponds to a first-order quantum phase transition between spherical and axially deformed shapes.
Quantum compositeness of gravity: black holes, AdS and inflation
Dvali, Gia; Gomez, Cesar E-mail: cesar.gomez@uam.es
2014-01-01
Gravitational backgrounds, such as black holes, AdS, de Sitter and inflationary universes, should be viewed as composite of N soft constituent gravitons. It then follows that such systems are close to quantum criticality of graviton Bose-gas to Bose-liquid transition. Generic properties of the ordinary metric description, including geodesic motion or particle-creation in the background metric, emerge as the large-N limit of quantum scattering of constituent longitudinal gravitons. We show that this picture correctly accounts for physics of large and small black holes in AdS, as well as reproduces well-known inflationary predictions for cosmological parameters. However, it anticipates new effects not captured by the standard semi-classical treatment. In particular, we predict observable corrections that are sensitive to the inflationary history way beyond last 60 e-foldings. We derive an absolute upper bound on the number of e-foldings, beyond which neither de Sitter nor inflationary Universe can be approximated by a semi-classical metric. However, they could in principle persist in a new type of quantum eternity state. We discuss implications of this phenomenon for the cosmological constant problem.
Quantum dynamics of fast chemical reactions
Light, J.C.
1993-12-01
The aims of this research are to explore, develop, and apply theoretical methods for the evaluation of the dynamics of gas phase collision processes, primarily chemical reactions. The primary theoretical tools developed for this work have been quantum scattering theory, both in time dependent and time independent forms. Over the past several years, the authors have developed and applied methods for the direct quantum evaluation of thermal rate constants, applying these to the evaluation of the hydrogen isotopic exchange reactions, applied wave packet propagation techniques to the dissociation of Rydberg H{sub 3}, incorporated optical potentials into the evaluation of thermal rate constants, evaluated the use of optical potentials for state-to-state reaction probability evaluations, and, most recently, have developed quantum approaches for electronically non-adiabatic reactions which may be applied to simplify calculations of reactive, but electronically adiabatic systems. Evaluation of the thermal rate constants and the dissociation of H{sub 3} were reported last year, and have now been published.
Duplex quantum communication through a spin chain
Wang Zhaoming; Gu Yongjian [Department of Physics, Ocean University of China, Qingdao 266100 (China); Bishop, C. Allen [Department of Physics, Southern Illinois University, Carbondale, Illinois 62901-4401 (United States); Shao Bin [Department of Physics, Beijing Institute of Technology, Beijing 100081 (China)
2011-08-15
Data multiplexing within a quantum computer can allow for the simultaneous transfer of multiple streams of information over a shared medium thereby minimizing the number of channels needed for requisite data transmission. Here, we investigate a two-way quantum communication protocol using a spin chain placed in an external magnetic field. In our scheme, Alice and Bob each play the role of a sender and a receiver as two states, cos(({theta}{sub 1}/2))0+sin(({theta}{sub 1}/2))e{sup i{phi}{sub 1}}1 and cos(({theta}{sub 2}/2))0+sin(({theta}{sub 2}/2))e{sup i{phi}{sub 2}}1, are transferred through one channel simultaneously. We find that the transmission fidelity at each end of a spin chain can usually be enhanced by the presence of a second party. This is an important result for establishing the viability of duplex quantum communication through spin chain networks.
Atomic quantum corrals for Bose-Einstein condensates
Xiong Hongwei [State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Kavli Institute for Theoretical Physics China, Chinese Academy of Sciences, Beijing 100190 (China); Wu Biao [Kavli Institute for Theoretical Physics China, Chinese Academy of Sciences, Beijing 100190 (China); International Center for Quantum Materials, Peking University, Beijing 100871 (China); Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)
2010-11-15
We consider the dynamics of Bose-Einstein condensates in a corral-like potential. Compared to the electronic quantum corrals, the atomic quantum corrals have the advantages of allowing direct and convenient observation of the wave dynamics, together with adjustable interaction strength. Our numerical study shows that these advantages not only allow exploration of the rich dynamical structures in the density distribution but also make the corrals useful in many other aspects. In particular, the corrals for atoms can be arranged into a stadium shape for the experimental visualization of quantum chaos, which has been elusive with electronic quantum corrals. The density correlation is used to describe quantitatively the dynamical quantum chaos. Furthermore, we find that the interatomic interaction can greatly enhance the dynamical quantum chaos, for example, inducing a chaotic behavior even in circle-shaped corrals.
Spectroscopic properties of colloidal indium phosphide quantum wires
Wang, Lin-Wang; Wang, Fudong; Yu, Heng; Li, Jingbo; Hang, Qingling; Zemlyanov, Dmitry; Gibbons, Patrick C.; Wang, Lin-Wang; Janes, David B.; Buhro, William E.
2008-07-11
Colloidal InP quantum wires are grown by the solution-liquid-solid (SLS) method, and passivated with the traditional quantum dots surfactants 1-hexadecylamine and tri-n-octylphosphine oxide. The size dependence of the band gaps in the wires are determined from the absorption spectra, and compared to other experimental results for InP quantum dots and wires, and to the predictions of theory. The photoluminescence behavior of the wires is also investigated. Efforts to enhance photoluminescence efficiencies through photochemical etching in the presence of HF result only in photochemical thinning or photo-oxidation, without a significant influence on quantum-wire photoluminescence. However, photo-oxidation produces residual dot and rod domains within the wires, which are luminescent. The results establish that the quantum-wire band gaps are weakly influenced by the nature of the surface passivation, and that colloidal quantum wires have intrinsically low photoluminescence efficiencies.
Semiconductor Quantum Rods as Single Molecule FluorescentBiological Labels
Fu, Aihua; Gu, Weiwei; Boussert, Benjamine; Koski, Kristie; Gerion, Daniele; Manna, Liberato; Le Gros, Mark; Larabell, Carolyn; Alivisatos, A. Paul
2006-05-29
In recent years, semiconductor quantum dots have beenapplied with great advantage in a wide range of biological imagingapplications. The continuing developments in the synthesis of nanoscalematerials and specifically in the area of colloidal semiconductornanocrystals have created an opportunity to generate a next generation ofbiological labels with complementary or in some cases enhanced propertiescompared to colloidal quantum dots. In this paper, we report thedevelopment of rod shaped semiconductor nanocrystals (quantum rods) asnew fluorescent biological labels. We have engineered biocompatiblequantum rods by surface silanization and have applied them fornon-specific cell tracking as well as specific cellular targeting. Theproperties of quantum rods as demonstrated here are enhanced sensitivityand greater resistance for degradation as compared to quantum dots.Quantum rods have many potential applications as biological labels insituations where their properties offer advantages over quantumdots.
Antenna factorization in strongly ordered limits
Kosower, David A.
2005-02-15
When energies or angles of gluons emitted in a gauge-theory process are small and strongly ordered, the emission factorizes in a simple way to all orders in perturbation theory. I show how to unify the various strongly ordered soft, mixed soft-collinear, and collinear limits using antenna factorization amplitudes, which are generalizations of the Catani-Seymour dipole factorization function.
Flexible moldable conductive current-limiting materials
Shea, John Joseph (Pittsburgh, PA); Djordjevic, Miomir B. (Milwaukee, WI); Hanna, William Kingston (Pittsburgh, PA)
2002-01-01
A current limiting PTC device (10) has two electrodes (14) with a thin film of electric conducting polymer material (20) disposed between the electrodes, the polymer material (20) having superior flexibility and short circuit performance, where the polymer material contains short chain aliphatic diepoxide, conductive filler particles, curing agent, and, preferably, a minor amount of bisphenol A epoxy resin.
Nanoscale engineering boosts performance of quantum dot light emitting
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diodes Quantum dot light emitting diodes Nanoscale engineering boosts performance of quantum dot light emitting diodes Quantum dots are nano-sized semiconductor particles whose emission color can be tuned by simply changing their dimensions. October 25, 2013 Postdoctoral researcher Young-Shin Park characterizing emission spectra of LEDs in the Los Alamos National Laboratory optical laboratory. Postdoctoral researcher Young-Shin Park characterizing emission spectra of LEDs in the Los Alamos
Observation of a Macroscopically Quantum-Entangled Insulator
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Observation of a Macroscopically Quantum-Entangled Insulator Observation of a Macroscopically Quantum-Entangled Insulator Print Wednesday, 27 May 2009 00:00 It has recently been proposed that insulators with large band gaps and strong spin-orbit coupling can host a new phase of quantum matter called a topological insulator that is characterized by entangled wavefunctions. The proposal has now been realized by an international collaboration led by researchers from Princeton University who studied
Optimal quantum control in nanostructures: Theory and application to a
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generic three-level system (Journal Article) | SciTech Connect Optimal quantum control in nanostructures: Theory and application to a generic three-level system Citation Details In-Document Search Title: Optimal quantum control in nanostructures: Theory and application to a generic three-level system Coherent carrier control in quantum nanostructures is studied within the framework of optimal control. We develop a general solution scheme for the optimization of an external control (e.g.,
Heavy pair production currents with general quantum numbers in
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dimensionally regularized nonrelativistic QCD (Journal Article) | SciTech Connect Heavy pair production currents with general quantum numbers in dimensionally regularized nonrelativistic QCD Citation Details In-Document Search Title: Heavy pair production currents with general quantum numbers in dimensionally regularized nonrelativistic QCD We discuss the form and construction of general color singlet heavy particle-antiparticle pair production currents for arbitrary quantum numbers, and
Measurement-only topological quantum computation via anyonic interferometry
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(Journal Article) | SciTech Connect Measurement-only topological quantum computation via anyonic interferometry Citation Details In-Document Search Title: Measurement-only topological quantum computation via anyonic interferometry We describe measurement-only topological quantum computation using both projective and interferometrical measurement of topological charge. We demonstrate how anyonic teleportation can be achieved using 'forced measurement' protocols for both types of measurement.
Correlated electron dynamics with time-dependent quantum Monte Carlo:
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Three-dimensional helium (Journal Article) | SciTech Connect Correlated electron dynamics with time-dependent quantum Monte Carlo: Three-dimensional helium Citation Details In-Document Search Title: Correlated electron dynamics with time-dependent quantum Monte Carlo: Three-dimensional helium Here the recently proposed time-dependent quantum Monte Carlo method is applied to three dimensional para- and ortho-helium atoms subjected to an external electromagnetic field with amplitude sufficient
Emerging Properties of Quantum Matter - Case Studies of Topological and
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Superconducting Phases (Conference) | SciTech Connect Conference: Emerging Properties of Quantum Matter - Case Studies of Topological and Superconducting Phases Citation Details In-Document Search Title: Emerging Properties of Quantum Matter - Case Studies of Topological and Superconducting Phases Emerging properties in quantum matter is a major theme of modern physics, with the promise that insights gained would have implications far beyond these materials. This talk will address two
Quantum and Dirac Materials for Energy Applications Conference (QDM-15)
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March Â» Quantum and Dirac Materials for Energy Applications Quantum and Dirac Materials for Energy Applications Conference (QDM-15) WHEN: Mar 08, 2015 8:00 AM - Mar 11, 2015 5:00 PM WHERE: La Fonda Hotel Santa Fe, NM CONTACT: Caryll Blount 505 665-3950 CATEGORY: Science TYPE: Conference INTERNAL: Calendar Login Event Description The purpose of the workshop is to discuss current status and future prospects for the quantum materials and Dirac materials for energy and information technology
Discontinuous Methods for Accurate, Massively Parallel Quantum Molecular
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Dynamics John Pask is Lead Prinicipal Investigator for Discontinuous Methods for Accurate, Massively Parallel Quantum Molecular Dynamics. Discontinuous Methods for Accurate, Massively Parallel Quantum Molecular Dynamics Research We develop and apply a recent breakthrough, the Discontinuous Galerkin electronic structure method, to reach for the first time the required length and time scales to attain a detailed quantum mechanical understanding of the chemistry and dynamics at the SEI layer in
COLLOQUIUM: Quantum Mechanics and Spacetime Geometry | Princeton Plasma
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Physics Lab February 25, 2014, 4:00pm to 5:30pm Colloquia MBG Auditorium COLLOQUIUM: Quantum Mechanics and Spacetime Geometry Professor Juan Maldacena Institute for Advanced Study Quantum mechanics is important for determining the geometry of spacetime. We will review the role of quantum fluctuations that determine the large scale structure of the universe. In some model universes we can give an alternative description of the physics in terms of a theory of particles that lives on its
Entanglement versus relaxation and decoherence in a quantum algorithm for quantum chaos
Bettelli, S.; Shepelyansky, D.L. [Laboratoire de Physique Quantique, UMR 5626 du CNRS, Universite Paul Sabatier, 31062 Toulouse Cedex 4 (France)
2003-05-01
We study analytically and numerically the behavior of the concurrence (a measure of the entanglement of formation) of a pair of qubits in a quantum computer operating an efficient algorithm for quantum chaos. Our results show that in an ideal algorithm the entanglement decays exponentially with the diffusive relaxation rate induced by classical chaos. This decay reaches a residual level which drops exponentially with increasing number of qubits n{sub q}. Decoherence destroys the residual entanglement with a rate exponential in n{sub q}.
Quantum optics with single nanodiamonds flying over gold films: Towards a Robust quantum plasmonics
Mollet, O.; Drezet, A.; Huant, S.
2013-12-04
A nanodiamond (ND) hosting nitrogen-vacancy (NV) color centers is attached on the apex of an optical tip for near-field microscopy. Its fluorescence is used to launch surface plasmon-polaritons (SPPs) in a thin polycrystalline gold film. It is shown that the quantum nature of the initial source of light is preserved after conversion to SPPs. This opens the way to a deterministic quantum plasmonics, where single SPPs can be injected at well-defined positions in a plasmonic device produced by top-down approaches.
Lorentz Invariant phenomenological model of quantum gravity: A minimalistic presentation
Bonder, Yuri
2012-08-24
The purpose of this paper is to give a minimalistic and self-contained presentation of a Lorentz Invariant phenomenological model of Quantum Gravity.
New parton distribution functions from a global analysis of quantum...
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New parton distribution functions from a global analysis of quantum chromodynamics ... Country of Publication: United States Language: English Word Cloud More Like This Free Publicly ...
Sandia Energy - Research Challenge 2: Quantum Dots and Phosphors
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2: Quantum Dots and Phosphors Home Energy Research EFRCs Solid-State Lighting Science EFRC Our SSLS EFRC's Scientific Research Challenges and Publications Research Challenge 2:...
Materials Frontiers to Empower Quantum Computing (Technical Report...
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and their origins in materials defects and environmental coupling. Realizing this vision systematically and predictively will be transformative for quantum computing and will...
Quantum cryptography put to work for electric grid security
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demonstration of securing control data for electric grids using quantum cryptography. ... research and prove emerging smart grid technology in a fully customizable environment. ...
Entanglement, Holography, and the Quantum Phases of Matter (Conference...
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I will discuss the impact of such ideas on studies of quantum phase transitions, and of novel metals. Authors: Sachdev, Subir 1 + Show Author Affiliations Harvard University ...
Quantum Oscillations from Nodal Bilayer Magnetic Breakdown in...
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Temperature Superconductor YBa2Cu3O6+x Citation Details In-Document Search Title: Quantum Oscillations from Nodal Bilayer Magnetic Breakdown in the Underdoped High Temperature ...
Quantum-Mechanical Interatomic Potentials with Electron Temperature...
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Electron Temperature for Strong Coupling Transition Metals Citation Details In-Document Search Title: Quantum-Mechanical Interatomic Potentials with Electron Temperature for ...
Universal Entanglement Entropy in 2D Conformal Quantum Critical...
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the properties of the conformal structure of the wave function of these quantum critical systems. The calculation of the universal term reduces to a problem in boundary conformal...
Quantum Materials Corporation formerly Hague Corp | Open Energy...
Corporation formerly Hague Corp Jump to: navigation, search Name: Quantum Materials Corporation (formerly Hague Corp) Sector: Renewable Energy Product: Through their wholly owned...
Robert B. Laughlin and the Fractional Quantum Hall Effect
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Robert B. Laughlin and the Fractional Quantum Hall Effect Resources with Additional Information Robert B. Laughlin Photo Courtesy of LLNL Robert B. Laughlin shared the 1998 Nobel...
Bob Lucas USC - Lockheed Martin Quantum Computing Center Information...
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the User's Knowledge of Resilience Bob Lucas USC - Lockheed Martin Quantum Computing Center Information Sciences Institute Viterbi School of Engineering Collaborators * USC Jacque...
Divergences of generalized quantum electrodynamics on the Lorenz gauge
Bufalo, R.; Pimentel, B. M.; Zambrano, G. E.
2013-03-25
In this paper we study the Generalized Quantum Electrodynamics (GQED4) on the Lorenz gauge condition and show that divergences are still present in the theory.
Baryon Spectrum from Superconformal Quantum Mechanics and its...
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Baryon Spectrum from Superconformal Quantum Mechanics and its Light-Front Holographic Embedding Citation Details In-Document Search Title: Baryon Spectrum from Superconformal...
ANALOG QUANTUM NEURON FOR FUNCTIONS APPROXIMATION A. EZHOV; A...
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FOR FUNCTIONS APPROXIMATION A. EZHOV; A. KHROMOV; G. BERMAN 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; IMPLEMENTATION; NERVE CELLS; WAVEGUIDES We describe a system able...
Scalable, High-Speed Measurement-Based Quantum Computer Using...
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University of Toronto, Toronto, Ontario M5S 1A7 (Canada) 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CALCIUM IONS; INFORMATION THEORY; MULTI-PHOTON PROCESSES;...
University) [Johns Hopkins University] 71 CLASSICAL AND QUANTUM...
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Zlatko (Johns Hopkins University) Johns Hopkins University 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY;...
Entanglement, Holography, and the Quantum Phases of Matter Sachdev...
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Matter Sachdev, Subir Harvard University 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS Electrons in many interesting materials, such as the high temperature...
Baryon Spectrum from Superconformal Quantum Mechanics and its...
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Journal Article: Baryon Spectrum from Superconformal Quantum Mechanics and its Light-Front Holographic Embedding Citation Details In-Document Search Title: Baryon Spectrum from...
Detection and measurement of electroreflectance on quantum cascade...
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Detection and measurement of electroreflectance on quantum cascade laser device using Fourier transform infrared microscope Citation Details In-Document Search Title: Detection and...
Evidence for an anomalous quantum state of protons in nanoconfined...
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of protons in nanoconfined water Citation Details In-Document Search Title: Evidence for an anomalous quantum state of protons in nanoconfined water Deep inelastic neutron ...
Quantum critical scaling and superconductivity in heavy electron...
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This content will become publicly available on November 16, 2016 Title: Quantum critical ... become publicly available on November 16, 2016 Publisher's Version of Record 10.1103...
Rigidifying Fluorescent Linkers by MOF Formation for Quantum Yield
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Enhancement | Center for Gas SeparationsRelevant to Clean Energy Technologies | Blandine Jerome Rigidifying Fluorescent Linkers by MOF Formation for Quantum Yield Enhancement
Experimental Observation of Quantum Oscillation of Surface Chemical Reactivities
Ma, X.; Jiang, P.; Qi, Y.; Jia, J.; Yang, Y.; Duan, W.; Li, W. X.; Bao, X.; Zhang, S. B.
2007-05-29
Here we present direct observation of a quantum reactivity with respect to the amounts of O2 adsorbed and the rates of surface oxidation as a function of film thickness on ultrathin (2-6 nm) Pb mesas by scanning tunneling microscopy. Simultaneous spectroscopic measurements on the electronic structures reveal a quantum oscillation that originates from quantum well states of the mesas, as a generalization of the Fabry-P{acute e}rot modes of confined electron waves. We expect the quantum reactivity to be a general phenomenon for most ultrathin metal films with broad implications, such as nanostructure tuning of surface reactivities and rational design of heterogeneous catalysts.
Tuning Into the Right Wavelength: Quantum Dot Rainbow Increases...
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Sequentially deposited green, orange, and red-emitting quantum dots serve as sensitizers ... converted more light than expected into energy compared with solar cells containing only ...
Miniscule Mirrored Cavities Connect Quantum Memories | U.S. DOE...
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Miniscule Mirrored Cavities Connect Quantum Memories Basic Energy Sciences (BES) BES Home ... Diamond optical cavities allow laser light (green arrow) to excite electrons on atoms held ...
Photovoltaic Cell Quantum Efficiency Basics | Department of Energy
Quantum Efficiency Basics Photovoltaic Cell Quantum Efficiency Basics August 20, 2013 - 3:05pm Addthis Quantum efficiency (QE) is the ratio of the number of charge carriers collected by a photovoltaic (PV) cell to the number of photons-or packets of light-of a given energy shining on the solar cell. Quantum efficiency therefore relates to the response of a solar cell to the various wavelengths in the spectrum of light shining on the cell. The QE is given as a function of either wavelength or
Quantum-Dots Based Electrochemical Immunoassay of Interleukin-1?
Wu, Hong; Liu, Guodong; Wang, Jun; Lin, Yuehe
2007-07-01
We describe a quantum-dot (QD, CdSe@ZnS)-based electrochemical immunoassay to detect a protein biomarker, interleukin-1? (IL-1?). QD conjugated with anti-IL-1? antibody was used as a label in an immunorecognition event. After a complete sandwich immunoreaction among the primary IL-1? antibody (immobilized on the avidin-modified magnetic beads), IL-1?, and the QD-labeled secondary antibody, QD labels were attached to the magnetic-bead surface through the antibody-antigen immunocomplex. Electrochemical stripping analysis of the captured QDs was used to quantify the concentration of IL-1? after an acid-dissolution step. The streptavidin-modified magnetic beads and the magnetic separation platform were used to integrate a facile antibody immobilization (through a biotin/streptavidin interaction) with immunoreactions and the isolation of immunocomplexes from reaction solutions in the assay. The voltammetric response is highly linear over the range of 0.5 to 50 ng mL-1 IL 1?, and the limit of detection is estimated to be 0.3 ng mL-1 (18 pM). This QD-based electrochemical immunoassay shows great promise for rapid, simple, and cost-effective analysis of protein biomarkers.
Transient quantum coherent response to a partially coherent radiation field
Sadeq, Zaheen S.; Brumer, Paul
2014-02-21
The response of an arbitrary closed quantum system to a partially coherent electric field is investigated, with a focus on the transient coherences in the system. As a model we examine, both perturbatively and numerically, the coherences induced in a three level V system. Both rapid turn-on and pulsed turn-on effects are investigated. The effect of a long and incoherent pulse is also considered, demonstrating that during the pulse the system shows a coherent response which reduces after the pulse is over. Both the pulsed scenario and the thermally broadened CW case approach a mixed state in the long time limit, with rates dictated by the adjacent level spacings and the coherence time of the light, and via a mechanism that is distinctly different from traditional decoherence. These two excitation scenarios are also explored for a minimal “toy” model of the electronic levels in pigment protein complex PC645 by both a collisionally broadened CW laser and by a noisy pulse, where unexpectedly long transient coherence times are observed and explained. The significance of environmentally induced decoherence is noted.
Nuclear structure at the limits of resolution: Looking through individual wave functions
Zelevinsky, V.G. [Michigan State Univ., East Lansing, MI (United States)
1996-12-31
60 years ago Niels Bohr suggested the idea of the compound nucleus. Bohr`s picture strongly resembles that of quantum chaos. Here one comes to the limits of resolution studying particular stationary states at high level density. Present knowledge comes from the experiment and from theoretical constructions, confirmed by the experiment at lower energies and extrapolated into the region where fine resolution measurements are not feasible. Such an analysis was carried out recently for heavy atoms and shell model nuclei. Among complicated states with the same values of integrals of motion, either (i) adjacent states have different structure or (ii) they {open_quotes}look the same{close_quotes} on the microscopic scale. Only (ii) corresponds to strong mixing assumed in the compound nucleus theory. Many-body chaos in nuclei is caused by residual interactions rather than by specific shape of the {open_quotes}container{close_quotes} as in quantum billiards. The shell model, including all degrees of freedom (in truncated space) along with the symmetry requirements, guarantees the correct level density up to some excitation energy. Therefore one can extrapolate the calculations into terra incognita of high lying states.
Vossier, Alexis Gualdi, Federico; Dollet, Alain; Ares, Richard; Aimez, Vincent
2015-01-07
In principle, the upper efficiency limit of any solar cell technology can be determined using the detailed-balance limit formalism. However, â€śrealâ€ť solar cells show efficiencies which are always below this theoretical value due to several limiting mechanisms. We study the ability of a solar cell architecture to approach its own theoretical limit, using a novel index introduced in this work, and the amplitude with which the different limiting mechanisms affect the cell efficiency is scrutinized as a function of the electronic gap and the illumination level to which the cell is submitted. The implications for future generations of solar cells aiming at an improved conversion of the solar spectrum are also addressed.
Deformation Quantization: Quantum Mechanic Lives and Works in Phase-Space
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(Conference) | SciTech Connect Conference: Deformation Quantization: Quantum Mechanic Lives and Works in Phase-Space Citation Details In-Document Search Title: Deformation Quantization: Quantum Mechanic Lives and Works in Phase-Space Wigner's 1932 quasi-probability Distribution Function in phase-space is a special (Weyl) representation of the density matrix. It has been useful in describing quantum flows in: quantum optics; nuclear physics; decoherence (eg, quantum computing); quantum chaos;
Toxicity Data to Determine Refrigerant Concentration Limits
Calm, James M.
2000-09-30
This report reviews toxicity data, identifies sources for them, and presents resulting exposure limits for refrigerants for consideration by qualified parties in developing safety guides, standards, codes, and regulations. It outlines a method to calculate an acute toxicity exposure limit (ATEL) and from it a recommended refrigerant concentration limit (RCL) for emergency exposures. The report focuses on acute toxicity with particular attention to lethality, cardiac sensitization, anesthetic and central nervous system effects, and other escape-impairing effects. It addresses R-11, R-12, R-22, R-23, R-113, R-114, R-116, R-123, R-124, R-125, R-134, R-134a, R-E134, R-141b, R-142b, R-143a, R-152a, R-218, R-227ea, R-236fa, R-245ca, R-245fa, R-290, R-500, R-502, R-600a, R-717, and R-744. It summarizes additional data for R-14, R-115, R-170 (ethane), R-C318, R-600 (n-butane), and R-1270 (propylene) to enable calculation of limits for blends incorporating them. The report summarizes the data a nd related safety information, including classifications and flammability data. It also presents a series of tables with proposed ATEL and RCL concentrations-in dimensionless form and the latter also in both metric (SI) and inch-pound (IP) units of measure-for both the cited refrigerants and 66 zerotropic and azeotropic blends. They include common refrigerants, such as R-404A, R-407C, R-410A, and R-507A, as well as others in commercial or developmental status. Appendices provide profiles for the cited single-compound refrigerants and for R-500 and R-502 as well as narrative toxicity summaries for common refrigerants. The report includes an extensive set of references.
DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS
P. Bernot
2005-07-13
The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of elements with radioactive isotopes under probable repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, field measurements, and laboratory experiments. The scope of this activity is to predict dissolved concentrations or solubility limits for elements with radioactive isotopes (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium) relevant to calculated dose. Model outputs for uranium, plutonium, neptunium, thorium, americium, and protactinium are provided in the form of tabulated functions with pH and log fCO{sub 2} as independent variables, plus one or more uncertainty terms. The solubility limits for the remaining elements are either in the form of distributions or single values. Even though selection of an appropriate set of radionuclides documented in Radionuclide Screening (BSC 2002 [DIRS 160059]) includes actinium, transport of Ac is not modeled in the total system performance assessment for the license application (TSPA-LA) model because of its extremely short half-life. Actinium dose is calculated in the TSPA-LA by assuming secular equilibrium with {sup 231}Pa (Section 6.10); therefore, Ac is not analyzed in this report. The output data from this report are fundamental inputs for TSPA-LA used to determine the estimated release of these elements from waste packages and the engineered barrier system. Consistent modeling approaches and environmental conditions were used to develop solubility models for the actinides discussed in this report. These models cover broad ranges of environmental conditions so they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, and activity coefficients have been quantified or otherwise addressed.
Means for limiting and ameliorating electrode shorting
Konynenburg, R.A. van; Farmer, J.C.
1999-11-09
A fuse and filter arrangement is described for limiting and ameliorating electrode shorting in capacitive deionization water purification systems utilizing carbon aerogel, for example. This arrangement limits and ameliorates the effects of conducting particles or debonded carbon aerogel in shorting the electrodes of a system such as a capacitive deionization water purification system. This is important because of the small interelectrode spacing and the finite possibility of debonding or fragmentation of carbon aerogel in a large system. The fuse and filter arrangement electrically protect the entire system from shutting down if a single pair of electrodes is shorted and mechanically prevents a conducting particle from migrating through the electrode stack, shorting a series of electrode pairs in sequence. It also limits the amount of energy released in a shorting event. The arrangement consists of a set of circuit breakers or fuses with one fuse or breaker in the power line connected to one electrode of each electrode pair and a set of screens of filters in the water flow channels between each set of electrode pairs.
Means for limiting and ameliorating electrode shorting
Van Konynenburg, Richard A. (Livermore, CA); Farmer, Joseph C. (Tracy, CA)
1999-01-01
A fuse and filter arrangement for limiting and ameliorating electrode shorting in capacitive deionization water purification systems utilizing carbon aerogel, for example. This arrangement limits and ameliorates the effects of conducting particles or debonded carbon aerogel in shorting the electrodes of a system such as a capacitive deionization water purification system. This is important because of the small interelectrode spacing and the finite possibility of debonding or fragmentation of carbon aerogel in a large system. The fuse and filter arrangement electrically protect the entire system from shutting down if a single pair of electrodes is shorted and mechanically prevents a conducting particle from migrating through the electrode stack, shorting a series of electrode pairs in sequence. It also limits the amount of energy released in a shorting event. The arrangement consists of a set of circuit breakers or fuses with one fuse or breaker in the power line connected to one electrode of each electrode pair and a set of screens of filters in the water flow channels between each set of electrode pairs.
Combined SM Higgs Limits at the Tevatron
Krumnack, N.
2009-10-01
We combine results from CDF and D{sup 0} on direct searches for a standard model (SM) Higgs boson (H) in p{bar p} collisions at the Fermilab Tevatron at {radical}s = 1.96 TeV. Compared to the previous Higgs Tevatron combination, more data and new channels WH {yields} {tau}{nu}b{bar b}, VH {yields} {tau}{tau}b{bar b}/jj{tau}{tau}, VH {yields} jjb{bar b}, t{bar t}H {yields} t{bar t}b{bar b} have been added. Most previously used channels have been reanalyzed to gain sensitivity. We use the latest parton distribution functions and gg {yields} H theoretical cross sections when comparing our limits to the SM predictions. With 2.0-3.6 fb{sup -1} of data analyzed at CDF, and 0.9-4.2 fb{sup -1} at D{sup 0}, the 95% C.L. upper limits on Higgs boson production are a factor of 2.5 (0.86) times the SM cross section for a Higgs boson mass of m{sub H} = 115 (165) GeV/c{sup 2}. Based on simulation, the corresponding median expected upper limits are 2.4 (1.1). The mass range excluded at 95% C.L. for a SM Higgs has been extended to 160 < m{sub H} < 170 GeV/c{sup 2}.
Regular and chaotic quantum dynamics in atom-diatom reactive collisions
Gevorkyan, A. S., E-mail: g_ashot@sci.a [IIAP/IAPP NAS of Armenia (Armenia); Bogdanov, A. V., E-mail: bogdanov@csa.r [Institute for High Performance Computing and Information Systems (Russian Federation); Nyman, G., E-mail: nyman@chem.gu.s [University of Gothenburg, Department of Chemistry (Sweden)
2008-05-15
A new microirreversible 3D theory of quantum multichannel scattering in the three-body system is developed. The quantum approach is constructed on the generating trajectory tubes which allow taking into account influence of classical nonintegrability of the dynamical quantum system. When the volume of classical chaos in phase space is larger than the quantum cell in the corresponding quantum system, quantum chaos is generated. The probability of quantum transitions is constructed for this case. The collinear collision of the Li + (FH) {sup {yields}}(LiF) + H system is used for numerical illustration of a system generating quantum (wave) chaos.
SAMQUA - Quantum Numbers of Compound Nuclear States for R-Matrix...
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SAMQUA - Quantum Numbers of Compound Nuclear States for R-Matrix Analyses Citation Details In-Document Search Title: SAMQUA - Quantum Numbers of Compound Nuclear States for ...
Weird quantum fluctuations of empty space-maybe (Science/AAAS...
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of empty space-maybe (ScienceAAAS) Empty space is anything but, according to quantum mechanics: Instead, it roils with quantum particles flitting in and out of...
Fractional Quantum Hall Effect at Landau Level Filling v=4/11...
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Fractional Quantum Hall Effect at Landau Level Filling v411. Citation Details In-Document Search Title: Fractional Quantum Hall Effect at Landau Level Filling v411. Abstract...
ONSET OF CHAOS IN A MODEL OF QUANTUM COMPUTATION G. BERMAN; ET...
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OF CHAOS IN A MODEL OF QUANTUM COMPUTATION G. BERMAN; ET AL 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 99 GENERAL AND MISCELLANEOUSMATHEMATICS, COMPUTING, AND...
High-Efficiency Quantum-Well Thermoelectrics for Waste Heat Power...
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High-Efficiency Quantum-Well Thermoelectrics for Waste Heat Power Generation High-Efficiency Quantum-Well Thermoelectrics for Waste Heat Power Generation 2005 Diesel Engine ...
Casimir effect in the nonequilibrium steady state of a quantum spin chain
Gonzalez-Cabrera, D. L.; Racz, Z.
2010-05-15
We present a fully microscopics-based calculation of the Casimir effect in a nonequilibrium system, namely, an energy-flux-driven quantum XX chain. The force between the walls (transverse-field impurities) is calculated in a nonequilibrium steady state which is prepared by letting the system evolve from an initial state with the two halves of the chain prepared at equilibrium at different temperatures. The steady state emerging in the large-time limit is homogeneous but carries an energy flux. The Casimir force in this nonequilibrium state is calculated analytically in the limit when the transverse fields are small. We find that the the Casimir force range is reduced compared to the equilibrium case, and suggest that the reason for this is the reduction of fluctuations in the flux-carrying steady state.
Statistical theory of Coulomb blockade oscillations: Quantum chaos in quantum dots
Jalabert, R.A.; Stone, A.D.; Alhassid, Y. (Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, Connecticut 06511 (United States))
1992-06-08
We develop a statistical theory of the amplitude of Coulomb blockade oscillations in semiconductor quantum dots based on the hypothesis that chaotic dynamics in the dot potential leads to behavior described by random-matrix theory. Breaking time-reversal symmetry is predicted to cause an experimentally observable change in the distribution of amplitudes. The theory is tested numerically and good agreement is found.
Quantum states for quantum processes: A toy model for ammonia inversion spectra
Arteca, Gustavo A. [Departement de Chimie et Biochimie and Biomolecular Sciences Programme, Laurentian University, Ramsey Lake Road, Sudbury, Ontario, Canada P3E 2C6 (Canada); Department of Physical Chemistry, Uppsala University, A ring ngstroemlaboratoriet, Box 259, S-751 05 Uppsala (Sweden); Tapia, O. [Department of Physical Chemistry, Uppsala University, A ring ngstroemlaboratoriet, Box 259, S-751 05 Uppsala (Sweden)
2011-07-15
Chemical transformations are viewed here as quantum processes modulated by external fields, that is, as shifts in reactant to product amplitudes within a quantum state represented by a linear (coherent) superposition of electronuclear basis functions; their electronic quantum numbers identify the ''chemical species.'' This basis set can be mapped from attractors built from a unique electronic configurational space that is invariant with respect to the nuclear geometry. In turn, the quantum numbers that label these basis functions and the semiclassical potentials for the electronic attractors may be used to derive reaction coordinates to monitor progress as a function of the applied field. A generalization of Feynman's three-state model for the ammonia inversion process illustrates the scheme; to enforce symmetry for the entire inversion process model and ensure invariance with respect to nuclear configurations, the three attractors and their basis functions are computed with a grid of fixed floating Gaussian functions. The external-field modulation of the effective inversion barrier is discussed within this conceptual approach. This analysis brings the descriptions of chemical processes near modern technologies that employ molecules to encode information by means of confinement and external fields.
Fault Current Limiters (FCL) Fact Sheet | Department of Energy
Fault Current Limiters (FCL) Fact Sheet Fault Current Limiters (FCL) Fact Sheet Plugging America Into the Future of Power: Superconducting & Solid-state Power Equipment What are Fault Current Limiters Why do we need Fault Current Limiters What are the benefits to utilities Fault Current Limiter projects PDF icon Fault Current Limiters More Documents & Publications An Assessment of Fault Current Limiter Testing Requirements Superconductivity Program Overview Superconductivity for Electric
Headquarters Facilities Master Security Plan - Chapter 2, Limited Areas,
Vault-Type Rooms and Temporary Limited Areas | Department of Energy 2, Limited Areas, Vault-Type Rooms and Temporary Limited Areas Headquarters Facilities Master Security Plan - Chapter 2, Limited Areas, Vault-Type Rooms and Temporary Limited Areas 2016 Headquarters Facilities Master Security Plan - Chapter 2, Limited Areas, Vault-Type Rooms and Temporary Limited Areas This chapter covers the establishment, maintenance, and termination of areas within HQ buildings where classified activities
Quantum effects in unimolecular reaction dynamics
Gezelter, J.D.
1995-12-01
This work is primarily concerned with the development of models for the quantum dynamics of unimolecular isomerization and photodissociation reactions. We apply the rigorous quantum methodology of a Discrete Variable Representation (DVR) with Absorbing Boundary Conditions (ABC) to these models in an attempt to explain some very surprising results from a series of experiments on vibrationally excited ketene. Within the framework of these models, we are able to identify the experimental signatures of tunneling and dynamical resonances in the energy dependence of the rate of ketene isomerization. Additionally, we investigate the step-like features in the energy dependence of the rate of dissociation of triplet ketene to form {sup 3}B{sub 1} CH{sub 2} + {sup 1}{sigma}{sup +} CO that have been observed experimentally. These calculations provide a link between ab initio calculations of the potential energy surfaces and the experimentally observed dynamics on these surfaces. Additionally, we develop an approximate model for the partitioning of energy in the products of photodissociation reactions of large molecules with appreciable barriers to recombination. In simple bond cleavage reactions like CH{sub 3}COCl {yields} CH{sub 3}CO + Cl, the model does considerably better than other impulsive and statistical models in predicting the energy distribution in the products. We also investigate ways of correcting classical mechanics to include the important quantum mechanical aspects of zero-point energy. The method we investigate is found to introduce a number of undesirable dynamical artifacts including a reduction in the above-threshold rates for simple reactions, and a strong mixing of the chaotic and regular energy domains for some model problems. We conclude by discussing some of the directions for future research in the field of theoretical chemical dynamics.
An upper limit to ground state energy fluctuations in nuclear masses
Hirsch, Jorge G.; Frank, Alejandro; Barea, Jose [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, AP 70-543, 04510 Mexico DF (Mexico); Velazquez, Victor [Departamento de Fisica, Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, AP 70-348, 04511 Mexico DF (Mexico); Isacker, Piet van [GANIL, BP 55027, F-14076 Caen Cedex 5 (France); Zuker, Andres P. [IReS, Ba27-CNRS/Universite Louis Pasteur BP 28, F-67037 Strasbourg Cedex 2 (France)
2007-02-12
Shell model calculations are employed to estimate un upper limit of statistical fluctuations in the nuclear ground state energies. In order to mimic the presence of quantum chaos associated with neutron resonances at energies between 6 to 10 MeV, calculations include random interactions in the upper shells. The upper bound for the energy fluctuations at mid-shell is shown to have the form {sigma}(A) {approx_equal} 20A-1.34 MeV. This estimate is consistent with the mass errors found in large shell model calculations along the N=126 line, and with local mass error estimated using the Garvey-Kelson relations, all being smaller than 100 keV.
Chaos in the low-lying collective states of even-even nuclei: Classical limit
Alhassid, Y.; Whelan, N. (Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, CT (USA) A. W. Wright Nuclear Structure Laboratory, Yale University, New Haven, CT (USA))
1991-06-01
We study the classical dynamical behavior of a family of Hamiltonians in the interacting boson model which describe the low-lying collective states of even-even nuclei. Two measures of classical chaos, the fractional volume of chaotic trajectories and the average largest Lyapunov exponent, are studied as a function of energy, angular momentum, and a parameter which interpolates between rotational and {gamma}-unstable nuclei. Near these two limits the dynamics is regular but in the transition region it becomes chaotic. The results agree with a previous study of quantum chaos in the corresponding quantal model, where spectral and {ital E}(2) intensity fluctuations were analyzed. Contrary to most previous numerical studies which were restricted to unrealistic models in two degrees of freedom, the present model is realistic and has five degrees of freedom. The latter correspond to the five quadrupole nuclear shape degrees of freedom.