Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:cond-mat/0107280

Quantum feedback control of a solid-state two-level system

Rusko Ruskov, Alexander N. Korotkov

Published Jul 13, 2001• 2 citations
arXivHTMLPDF

Abstract

We have studied theoretically the basic operation of a quantum feedback loop designed to maintain the desired phase of quantum coherent oscillations in a two-level system. Such feedback can suppress the dephasing of oscillations due to interaction with environment. Prospective experiments can be realized using metallic single-electron devices or GaAs technology.

DOI
10.48550/arxiv.cond-mat/0107280

Related papers

Quantum feedback control of a solid-state qubit

Rusko Ruskov, Alexander N. Korotkov

We have studied theoretically the basic operation of a quantum feedback loop designed to maintain a desired phase of quantum coherent oscillations in a single solid-state qubit. The degree of oscillations synchronization with external harmonic signal is calculated as a function of feedback strength, taking into account available bandwidth and coupling to environment. The feedback can efficiently suppress the dephasing of oscillations if the qubit coupling to the detector is stronger than the coupling to the environment.

arXiv:cond-mat/0204516•Physical review. B, Condensed matter•Jun 28, 2002•96 citations

Quantum feedback control of coherent oscillations in a solid-state qubit

Rusko Ruskov, Q. Zhang, Alexander N. Korotkov

The performance of a quantum feedback loop designed to maintain a desired phase of quantum coherent oscillations in a single solid-state qubit is analyzed using the quantum Bayesian formalism. The degree of oscillations synchronization with classical reference signal is calculated as a function of feedback strength, taking also into account finite detector bandwidth, dephasing due to environment, and qubit energy asymmetry.

IEEE Conference on Decision and Control (CDC)•Apr 23, 2004•0 citations

Maintaining coherent oscillations in a solid-state qubit via continuous quantum feedback control

Rusko Ruskov, Qin Zhang, Alexander N. Korotkov

We discuss the operation of the one-qubit quantum feedback loop, which may be used for initialization of a qubit in a solid-state quantum computer. The continuous monitoring of a quantum state, which makes the feedback possible, is done by means of a weak continuous measurement and processing of the obtained information via quantum Bayesian equations. The properly designed quantum feedback loop can keep the desired phase of a single-qubit quantum coherent oscillations for infinitely long time, even in presence of a dephasing environment. Various nonidealities reduce the fidelity of the feedback synchronization. We report our study of the effects of finite available bandwidth and time delay on the one-qubit quantum feedback performance, and also discuss the effect of environment-induced dephasing.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Aug 24, 2004•3 citations

Simple quantum feedback of a solid-state qubit

Alexander N. Korotkov

We propose an experiment on quantum feedback control of a solid-state qubit, which is within the reach of the present-day technology. Similar to an earlier proposal [R. Ruskov and A. N. Korotkov, Phys. Rev. B 66, 041401(R) (2002)], the feedback loop is used to maintain coherent oscillations in a qubit for an arbitrarily long time; however, this is done in a significantly simpler way, which eases the bandwidth problem. The main idea is to use the quadrature components of the noisy detector current to monitor approximately the phase of qubit oscillations. The price for simplicity is a less-than-ideal operation: the fidelity is limited to about 95%. The feedback loop operation can be experimentally verified by the appearance of a positive in-phase component of the detector current relative to an external oscillating signal used for synchronization.

arXiv:cond-mat/0404696•Physical Review B•May 19, 2005•32 citations

Continuous quantum feedback of coherent oscillations in a solid-state qubit

Qin Zhang, Rusko Ruskov, Alexander N. Korotkov

We have analyzed theoretically the operation of the Bayesian quantum feedback of a solid-state qubit, designed to maintain perfect coherent oscillations in the qubit for arbitrarily long time. In particular, we have studied the feedback efficiency in presence of dephasing environment and detector nonideality. Also, we have analyzed the effect of qubit parameter deviations and studied the quantum feedback control of an energy-asymmetric qubit.

arXiv:cond-mat/0507011•Physical Review B•Dec 16, 2005•24 citations

Non-ideal quantum feedback of a solid-state qubit

Qin Zhang, Rusko Ruskov, Alexander N. Korotkov

We have analyzed the operation of the Bayesian quantum feedback of a solid-state qubit, designed to maintain perfect coherent oscillations in the qubit for arbitrarily long time. In particular, we have studied the feedback efficiency in presence of dephasing environment and detector nonideality. Also, we have investigated the effect of qubit parameter deviation.

Journal of Physics Conference Series•May 10, 2006•0 citations
We have studied theoretically the basic operation of a quantum feedback loop designed to maintain the desired phase of quantum coherent oscillations in a two-level system. Such feedback can suppress the dephasing of oscillations due to interaction with environment. Prospective experiments can be realized using metallic single-electron devices or GaAs technology.
We have studied theoretically the basic operation of a quantum feedback loop designed to maintain a desired phase of quantum coherent oscillations in a single solid-state qubit. The degree of oscillations synchronization with external harmonic signal is calculated as a function of feedback strength, taking into account available bandwidth and coupling to environment. The feedback can efficiently suppress the dephasing of oscillations if the qubit coupling to the detector is stronger than the coupling to the environment.
We discuss the operation of the one-qubit quantum feedback loop, which may be used for initialization of a qubit in a solid-state quantum computer. The continuous monitoring of a quantum state, which makes the feedback possible, is done by means of a weak continuous measurement and processing of the obtained information via quantum Bayesian equations. The properly designed quantum feedback loop can keep the desired phase of a single-qubit quantum coherent oscillations for infinitely long time, even in presence of a dephasing environment. Various nonidealities reduce the fidelity of the feedback synchronization. We report our study of the effects of finite available bandwidth and time delay on the one-qubit quantum feedback performance, and also discuss the effect of environment-induced dephasing.
We propose an experiment on quantum feedback control of a solid-state qubit, which is within the reach of the present-day technology. Similar to an earlier proposal [R. Ruskov and A. N. Korotkov, Phys. Rev. B 66, 041401(R) (2002)], the feedback loop is used to maintain coherent oscillations in a qubit for an arbitrarily long time; however, this is done in a significantly simpler way, which eases the bandwidth problem. The main idea is to use the quadrature components of the noisy detector current to monitor approximately the phase of qubit oscillations. The price for simplicity is a less-than-ideal operation: the fidelity is limited to about 95%. The feedback loop operation can be experimentally verified by the appearance of a positive in-phase component of the detector current relative to an external oscillating signal used for synchronization.