Fluctuations of the number of particles within a given volume in cold quantum gases

Astrakharchik, G E; Combescot, R; Pitaevskii, L P

doi:10.1103/PHYSREVA.76.063616

Title: Fluctuations of the number of particles within a given volume in cold quantum gases

Full Record
Other Related Research

Abstract

In ultracold gases many experiments use atom imaging as a basic observable. The resulting image is averaged over a number of realizations and mostly only this average is used. Only recently the noise has been measured to extract physical information. In the present paper we investigate the quantum noise arising in these gases at zero temperature. We restrict ourselves to the homogeneous situation and study the fluctuations in particle number found within a given volume in the gas, and more specifically inside a sphere of radius R. We show that zero-temperature fluctuations are not extensive and the leading term scales with sphere radius R as R{sup 2} ln R (or ln R) in three- (or one-) dimensional systems. We calculate systematically the next term beyond this leading order. We consider first the generic case of a compressible superfluid. Then we investigate the whole Bose-Einstein-condensation (BEC) -BCS crossover, and in particular the limiting cases of the weakly interacting Bose gas and of the free Fermi gas.

Authors:

Astrakharchik, G E ^[1]; Combescot, R ^[2]; Pitaevskii, L P ^[3]

Departament de Fisica i Enginyeria Nuclear, Campus Nord B4-B5, Universitat Politecnica de Catalunya, E-08034 Barcelona (Spain)
Laboratoire de Physique Statistique, Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris Cedex 05 (France)
Dipartimento di Fisica, Universita di Trento and BEC-INFM, I-38050 Povo, Italy and Kapitza Institute for Physical Problems, 119334 Moscow (Russian Federation)

Publication Date:: Sat Dec 15 00:00:00 EST 2007

OSTI Identifier:: 21140688

Resource Type:: Journal Article

Journal Name:: Physical Review. A

Additional Journal Information:: Journal Volume: 76; Journal Issue: 6; Other Information: DOI: 10.1103/PhysRevA.76.063616; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1050-2947

Country of Publication:: United States

Language:: English

Subject:: 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ATOMS; BCS THEORY; BOSE-EINSTEIN CONDENSATION; BOSE-EINSTEIN GAS; BOSONS; FERMI GAS; FERMIONS; FLUCTUATIONS; GASES; NOISE; ONE-DIMENSIONAL CALCULATIONS; PARTICLES; SUPERFLUIDITY; TEMPERATURE RANGE 0000-0013 K; WEAK INTERACTIONS

Citation Formats


                    Astrakharchik, G E, Combescot, R, and Pitaevskii, L P. Fluctuations of the number of particles within a given volume in cold quantum gases.  United States: N. p., 2007. 
        Web.  doi:10.1103/PHYSREVA.76.063616.

Copy to clipboard


                    Astrakharchik, G E, Combescot, R, & Pitaevskii, L P. Fluctuations of the number of particles within a given volume in cold quantum gases.  United States.  https://doi.org/10.1103/PHYSREVA.76.063616

Copy to clipboard


                    Astrakharchik, G E, Combescot, R, and Pitaevskii, L P. 2007.  
        "Fluctuations of the number of particles within a given volume in cold quantum gases".  United States.  https://doi.org/10.1103/PHYSREVA.76.063616.

Copy to clipboard


                    
@article{osti_21140688,

  title        = {Fluctuations of the number of particles within a given volume in cold quantum gases},

  author       = {Astrakharchik, G E and Combescot, R and Pitaevskii, L P},

  abstractNote = {In ultracold gases many experiments use atom imaging as a basic observable. The resulting image is averaged over a number of realizations and mostly only this average is used. Only recently the noise has been measured to extract physical information. In the present paper we investigate the quantum noise arising in these gases at zero temperature. We restrict ourselves to the homogeneous situation and study the fluctuations in particle number found within a given volume in the gas, and more specifically inside a sphere of radius R. We show that zero-temperature fluctuations are not extensive and the leading term scales with sphere radius R as R{sup 2} ln R (or ln R) in three- (or one-) dimensional systems. We calculate systematically the next term beyond this leading order. We consider first the generic case of a compressible superfluid. Then we investigate the whole Bose-Einstein-condensation (BEC) -BCS crossover, and in particular the limiting cases of the weakly interacting Bose gas and of the free Fermi gas.},

  doi          = {10.1103/PHYSREVA.76.063616},

  url          = {https://www.osti.gov/biblio/21140688},
  journal      = {Physical Review. A},

  issn         = {1050-2947},

  number       = 6,

  volume       = 76,

  place        = {United States},

  year         = {Sat Dec 15 00:00:00 EST 2007},

  month        = {Sat Dec 15 00:00:00 EST 2007}

}

Copy to clipboard

Journal Article:

https://doi.org/10.1103/PHYSREVA.76.063616

Other availability

Find in Google Scholar

Search WorldCat to find libraries that may hold this journal

Save / Share:

Export Metadata

Save to My Library

Similar records in OSTI.GOV collections:

Superfluidity and collective modes in a uniform gas of Fermi atoms with a Feshbach resonance

Journal Article Ohashi, Y; Griffin, A - Physical Review. A

We investigate strong-coupling superfluidity in a uniform two-component gas of ultracold Fermi atoms attractively interacting via quasimolecular bosons associated with a Feshbach resonance. This interaction is tunable by the threshold energy 2{nu} of the Feshbach resonance, becoming large as 2{nu} is decreased (relative to 2{epsilon}{sub F}, where {epsilon}{sub F} is the Fermi energy of one component). In recent work, we showed that the enhancement of this tunable pairing interaction naturally leads to the BCS-BEC (Bose-Einstein condensation) crossover, where the character of the superfluid phase transition changes from the BCS type to a BEC of composite bosons consisting of preformed Cooper-pairsmore »« less
https://doi.org/10.1103/PhysRevA.67.063612
Resonantly paired fermionic superfluids

Journal Article Gurarie, V; Radzihovsky, L - Annals of Physics (New York)

We present a theory of a degenerate atomic Fermi gas, interacting through a narrow Feshbach resonance, whose position and therefore strength can be tuned experimentally, as demonstrated recently in ultracold trapped atomic gases. The distinguishing feature of the theory is that its accuracy is controlled by a dimensionless parameter proportional to the ratio of the width of the resonance to Fermi energy. The theory is therefore quantitatively accurate for a narrow Feshbach resonance. In the case of a narrow s-wave resonance, our analysis leads to a quantitative description of the crossover between a weakly paired BCS superconductor of overlapping Coopermore »« less
https://doi.org/10.1016/j.aop.2006.10.009
Universality in phase transitions for ultracold fermionic atoms

Journal Article Diehl, S; Wetterich, C - Physical Review. A

We describe the gas of ultracold fermionic atoms by a functional integral for atom and molecule fields. The crossover from Bose-Einstein condensation (BEC) to BCS-type superfluidity shows universal features in terms of a concentration parameter for the ratio between scattering length and average interatomic distance. We discuss the relevance of the Yukawa coupling between atoms and molecules, establish an exact narrow resonance limit, and show that renormalized quantities are independent of the Yukawa coupling for the broad resonance and BCS and BEC limits. Within our functional integral formalism we compute the atom scattering in vacuum and the molecular binding energy.more »« less
https://doi.org/10.1103/PHYSREVA.73.0
Auxiliary field formalism for dilute fermionic atom gases with tunable interactions

Journal Article Mihaila, Bogdan; Chien, Chih-Chun; Timmermans, Eddy; ... - Physical Review. A

We develop the auxiliary field formalism corresponding to a dilute system of spin-1/2 fermions. This theory represents the Fermi counterpart of the Bose-Einstein condensation (BEC) theory developed recently by F. Cooper et al. [Phys. Rev. Lett. 105, 240402 (2010)] to describe a dilute gas of Bose particles. Assuming tunable interactions, this formalism is appropriate for the study of the crossover from the regime of Bardeen-Cooper-Schriffer (BCS) pairing to the regime of BEC in ultracold fermionic atom gases. We show that when applied to the Fermi case at zero temperature, the leading-order auxiliary field (LOAF) approximation gives the same equations asmore »« less
https://doi.org/10.1103/PHYSREVA.83.053637
Nonzero orbital angular momentum superfluidity in ultracold Fermi gases

Journal Article Iskin, M - Physical Review. A

We analyze the evolution of superfluidity for nonzero orbital angular momentum channels from the Bardeen-Cooper-Schrieffer (BCS) to the Bose-Einstein condensation (BEC) limit in three dimensions. First, we analyze the low-energy scattering properties of finite range interactions for all possible angular momentum channels. Second, we discuss ground-state (T=0) superfluid properties including the order parameter, chemical potential, quasiparticle excitation spectrum, momentum distribution, atomic compressibility, ground-state energy, and low-energy collective excitations. We show that a quantum phase transition occurs for nonzero angular momentum pairing, unlike the s-wave case where the BCS to BEC evolution is just a crossover. Third, we present a Gaussianmore »« less
https://doi.org/10.1103/PHYSREVA.74.013608

Similar Records