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Title: Quantum-information processing with circuit quantum electrodynamics

Abstract

We theoretically study single and two-qubit dynamics in the circuit QED architecture. We focus on the current experimental design [Wallraff et al., Nature (London) 431, 162 (2004); Schuster et al., ibid. 445, 515 (2007)] in which superconducting charge qubits are capacitively coupled to a single high-Q superconducting coplanar resonator. In this system, logical gates are realized by driving the resonator with microwave fields. Advantages of this architecture are that it allows for multiqubit gates between non-nearest qubits and for the realization of gates in parallel, opening the possibility of fault-tolerant quantum computation with superconducting circuits. In this paper, we focus on one- and two-qubit gates that do not require moving away from the charge-degeneracy sweet spot'. This is advantageous as it helps to increase the qubit dephasing time and does not require modification of the original circuit QED. However, these gates can, in some cases, be slower than those that do not use this constraint. Five types of two-qubit gates are discussed, these include gates based on virtual photons, real excitation of the resonator, and a gate based on the geometric phase. We also point out the importance of selection rules when working at the charge degeneracy point.

Authors:
 [1];  [2]; ; ; ; ;  [1];  [1];  [3]
  1. Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520 (United States)
  2. (Canada)
  3. (Switzerland)
Publication Date:
OSTI Identifier:
20982275
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 75; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevA.75.032329; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; INFORMATION THEORY; JOSEPHSON EFFECT; MICROWAVE RADIATION; MODIFICATIONS; PHOTONS; QUANTUM COMPUTERS; QUANTUM ELECTRODYNAMICS; QUANTUM MECHANICS; QUBITS; RESONATORS; SELECTION RULES

Citation Formats

Blais, Alexandre, Departement de Physique et Regroupement Quebecois sur les Materiaux de Pointe, Universite de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Gambetta, Jay, Schuster, D. I., Girvin, S. M., Devoret, M. H., Schoelkopf, R. J., Wallraff, A., and Department of Physics, ETH Zurich, CH-8093 Zuerich. Quantum-information processing with circuit quantum electrodynamics. United States: N. p., 2007. Web. doi:10.1103/PHYSREVA.75.032329.
Blais, Alexandre, Departement de Physique et Regroupement Quebecois sur les Materiaux de Pointe, Universite de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Gambetta, Jay, Schuster, D. I., Girvin, S. M., Devoret, M. H., Schoelkopf, R. J., Wallraff, A., & Department of Physics, ETH Zurich, CH-8093 Zuerich. Quantum-information processing with circuit quantum electrodynamics. United States. doi:10.1103/PHYSREVA.75.032329.
Blais, Alexandre, Departement de Physique et Regroupement Quebecois sur les Materiaux de Pointe, Universite de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Gambetta, Jay, Schuster, D. I., Girvin, S. M., Devoret, M. H., Schoelkopf, R. J., Wallraff, A., and Department of Physics, ETH Zurich, CH-8093 Zuerich. Thu . "Quantum-information processing with circuit quantum electrodynamics". United States. doi:10.1103/PHYSREVA.75.032329.
@article{osti_20982275,
title = {Quantum-information processing with circuit quantum electrodynamics},
author = {Blais, Alexandre and Departement de Physique et Regroupement Quebecois sur les Materiaux de Pointe, Universite de Sherbrooke, Sherbrooke, Quebec J1K 2R1 and Gambetta, Jay and Schuster, D. I. and Girvin, S. M. and Devoret, M. H. and Schoelkopf, R. J. and Wallraff, A. and Department of Physics, ETH Zurich, CH-8093 Zuerich},
abstractNote = {We theoretically study single and two-qubit dynamics in the circuit QED architecture. We focus on the current experimental design [Wallraff et al., Nature (London) 431, 162 (2004); Schuster et al., ibid. 445, 515 (2007)] in which superconducting charge qubits are capacitively coupled to a single high-Q superconducting coplanar resonator. In this system, logical gates are realized by driving the resonator with microwave fields. Advantages of this architecture are that it allows for multiqubit gates between non-nearest qubits and for the realization of gates in parallel, opening the possibility of fault-tolerant quantum computation with superconducting circuits. In this paper, we focus on one- and two-qubit gates that do not require moving away from the charge-degeneracy sweet spot'. This is advantageous as it helps to increase the qubit dephasing time and does not require modification of the original circuit QED. However, these gates can, in some cases, be slower than those that do not use this constraint. Five types of two-qubit gates are discussed, these include gates based on virtual photons, real excitation of the resonator, and a gate based on the geometric phase. We also point out the importance of selection rules when working at the charge degeneracy point.},
doi = {10.1103/PHYSREVA.75.032329},
journal = {Physical Review. A},
number = 3,
volume = 75,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
  • In this Brief Report, we propose a potential scheme to implement one-way quantum computation with circuit quantum electrodynamics (QED). Large cluster states of charge qubits can be generated in just one step with a superconducting transmission line resonator (TLR) playing the role of a dispersive coupler. A single-qubit measurement in the arbitrary basis can be implemented using a single electron transistor with the help of one-qubit gates. By examining the main decoherence sources, we show that circuit QED is a promising architecture for one-way quantum computation.
  • We evaluate the charge noise acting on a GaAs/GaAlAs based semiconductor double quantum dot dipole-coupled to the voltage oscillations of a superconducting transmission line resonator. The in-phase (I) and the quadrature (Q) components of the microwave tone transmitted through the resonator are sensitive to charging events in the surrounding environment of the double dot with an optimum sensitivity of 8.5×10{sup −5} e/√(Hz). A low frequency 1/f type noise spectrum combined with a white noise level of 6.6×10{sup −6} e{sup 2}/Hz above 1 Hz is extracted, consistent with previous results obtained with quantum point contact charge detectors on similar heterostructures. The slope ofmore » the 1/f noise allows to extract a lower bound for the double-dot charge qubit dephasing rate which we compare to the one extracted from a Jaynes-Cummings Hamiltonian approach. The two rates are found to be similar emphasizing that charge noise is the main source of dephasing in our system.« less
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  • The quantum state of a superconducting qubit nonresonantly coupled to a transmission line resonator can be determined by measuring the quadrature amplitudes of an electromagnetic field transmitted through the resonator. We present experiments in which we analyze in detail the dynamics of the transmitted field as a function of the measurement frequency for both weak continuous and pulsed measurements. We find excellent agreement between our data and calculations based on a set of Bloch-type differential equations for the cavity field derived from the dispersive Jaynes-Cummings Hamiltonian including dissipation. We show that the measured system response can be used to constructmore » a measurement operator from which the qubit population can be inferred accurately. Such a measurement operator can be used in tomographic methods to reconstruct single and multiqubit states in ensemble-averaged measurements.« less
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