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:quant-ph/0605044

Information Extraction from Decohering Systems via Indirect Continuous Measurement

Narayan Ganesan, Tzyh‐Jong Tarn

Published May 4, 2006• 0 citations
arXivHTMLPDF

Abstract

In this article we discuss a general information extraction scheme to gain knowledge of the state and the amount of decoherence based on indirect continuous measurement. The purpose of this information extraction is to determine the feedback in order to control decoherence based on an ``output equation", described by a bilinear form. An interacting bilinear form of control system is used instead of master equation to analyze the dynamic properties of the system. The analysis of continuous measurement on a decohering quantum system has not been extensively studied before.

DOI
10.48550/arxiv.quant-ph/0605044

Related papers

Decoherence control in open quantum systems via classical feedback

Narayan Ganesan, Tzyh‐Jong Tarn

In this work we propose a strategy using techniques from systems theory to completely eliminate decoherence and also provide conditions under which it can be done. A construction employing an auxiliary system, the bait, which is instrumental to decoupling the system from the environment is presented. Our approach to decoherence control in contrast to other approaches in the literature involves the bilinear input affine model of quantum control system which lends itself to various techniques from classical control theory, but with nontrivial modifications to the quantum regime. The elegance of this approach yields interesting results on open loop decouplability and decoherence free subspaces. Additionally, the feedback control of decoherence may be related to disturbance decoupling for classical input affine systems, which entails careful application of the methods by avoiding all the quantum mechanical pitfalls. In the process of calculating a suitable feedback the system must be restructured due to its tensorial nature of interaction with the environment, which is unique to quantum systems. In the subsequent section we discuss a general information extraction scheme to gain knowledge of the state and the amount of decoherence based on indirect continuous measurement. The analysis of continuous measurement on a decohering quantum system has not been extensively studied before. Finally, a methodology to synthesize feedback parameters itself is given, that technology permitting, could be implemented for practical 2-qubit systems to perform decoherence free quantum computing. The results obtained are qualitatively different and superior to the ones obtained via master equations.

arXiv:quant-ph/0611281•Physical Review A•Mar 19, 2007•41 citations

Feedback control of Decoherence by continuous measurement

Narayan Ganesan, Tarn, T J

A general framework for applying feedback control to quantum control system under continuous measurement by a probe is discussed. The analysis is the standard bilinear interacting hamiltonian control form. A continuous measurement model based on an interacting quantum probe is used to control via feedback. It is also shown that concepts from systems theory could be applied with non-trivial modifications to analyze such feedback control systems undergoing decoherence. We also report new progress to the ongoing work on applications of feedback to control decoherence in open quantum systems.

•May 4, 2006•0 citations

Control of decoherence in open quantum systems using feedback

Narayan Ganesan, Tzyh-jong Tarn

Abstract — Quantum feedback is assuming increasingly important role in quantum control and quantum information processing. In this work we analyze the application of such feedback techniques in eliminating decoherence in open quantum systems. In order to apply such system theoretic methods we first analyze the invariance properties of quadratic forms which corresponds to expected value of a measurement and present conditions for decouplability of measurement outputs of such time-varying open quantum systems from environmental effects. I.

•Jan 1, 2006•5 citations

Output feedback control of quantum mechanical systems

Wu Re-bing

Abstrcat The modeling and design of output feedback control of quantum systems are studied. Firstly, the compatibility of Von Neumann measurement principle and continuous measurement is discussed. Then based on the continuous measurement and the existed quantum feedback control schemes, the general models of output feedback control of quantum systems are summarized. Finally, the linear direct output feedback control strategy is applied to suppress the amplitude decoherence in quantum computers. It is shown that good results can be obtained by optimally designed proportional coefficient of the linear output feedback control.

Kongzhi yu juece•Jan 1, 2005•0 citations

Control of decoherence in open quantum systems using feedback

N. Ganesan, Tzyh-Jong Tarn

Quantum feedback is assuming increasingly im- portant role in quantum control and quantum information processing. In this work we analyze the application of such feedback techniques in eliminating decoherence in open quan- tum systems. In order to apply such system theoretic methods we first analyze the invariance properties of quadratic forms which corresponds to expected value of a measurement and present conditions for decouplability of measurement outputs of such time-varying open quantum systems from environmental effects.

arXiv:quant-ph/0602217•IEEE Conference on Decision and Control (CDC)•Oct 4, 2006•3 citations

Quantum Fokker-Planck Master Equation for Continuous Feedback Control

Björn Annby-Andersson, Pharnam Bakhshinezhad, Debankur Bhattacharyya +4 more

Measurement and feedback control are essential features of quantum science, with applications ranging from quantum technology protocols to information-to-work conversion in quantum thermodynamics. Theoretical descriptions of feedback control are typically given in terms of stochastic equations requiring numerical solutions, or are limited to linear feedback protocols. Here we present a formalism for continuous quantum measurement and feedback, both linear and nonlinear. Our main result is a quantum Fokker-Planck master equation describing the joint dynamics of a quantum system and a detector with finite bandwidth. For fast measurements, we derive a Markovian master equation for the system alone, amenable to analytical treatment. We illustrate our formalism by investigating two basic information engines, one quantum and one classical.

arXiv:2110.09159•Physical Review Letters•Jul 25, 2022•29 citations
In this article we discuss a general information extraction scheme to gain knowledge of the state and the amount of decoherence based on indirect continuous measurement. The purpose of this information extraction is to determine the feedback in order to control decoherence based on an ``output equation", described by a bilinear form. An interacting bilinear form of control system is used instead of master equation to analyze the dynamic properties of the system. The analysis of continuous measurement on a decohering quantum system has not been extensively studied before.
In this work we propose a strategy using techniques from systems theory to completely eliminate decoherence and also provide conditions under which it can be done. A construction employing an auxiliary system, the bait, which is instrumental to decoupling the system from the environment is presented. Our approach to decoherence control in contrast to other approaches in the literature involves the bilinear input affine model of quantum control system which lends itself to various techniques from classical control theory, but with nontrivial modifications to the quantum regime. The elegance of this approach yields interesting results on open loop decouplability and decoherence free subspaces. Additionally, the feedback control of decoherence may be related to disturbance decoupling for classical input affine systems, which entails careful application of the methods by avoiding all the quantum mechanical pitfalls. In the process of calculating a suitable feedback the system must be restructured due to its tensorial nature of interaction with the environment, which is unique to quantum systems. In the subsequent section we discuss a general information extraction scheme to gain knowledge of the state and the amount of decoherence based on indirect continuous measurement. The analysis of continuous measurement on a decohering quantum system has not been extensively studied before. Finally, a methodology to synthesize feedback parameters itself is given, that technology permitting, could be implemented for practical 2-qubit systems to perform decoherence free quantum computing. The results obtained are qualitatively different and superior to the ones obtained via master equations.
A general framework for applying feedback control to quantum control system under continuous measurement by a probe is discussed. The analysis is the standard bilinear interacting hamiltonian control form. A continuous measurement model based on an interacting quantum probe is used to control via feedback. It is also shown that concepts from systems theory could be applied with non-trivial modifications to analyze such feedback control systems undergoing decoherence. We also report new progress to the ongoing work on applications of feedback to control decoherence in open quantum systems.
Abstract — Quantum feedback is assuming increasingly important role in quantum control and quantum information processing. In this work we analyze the application of such feedback techniques in eliminating decoherence in open quantum systems. In order to apply such system theoretic methods we first analyze the invariance properties of quadratic forms which corresponds to expected value of a measurement and present conditions for decouplability of measurement outputs of such time-varying open quantum systems from environmental effects. I.
Abstrcat The modeling and design of output feedback control of quantum systems are studied. Firstly, the compatibility of Von Neumann measurement principle and continuous measurement is discussed. Then based on the continuous measurement and the existed quantum feedback control schemes, the general models of output feedback control of quantum systems are summarized. Finally, the linear direct output feedback control strategy is applied to suppress the amplitude decoherence in quantum computers. It is shown that good results can be obtained by optimally designed proportional coefficient of the linear output feedback control.
Quantum feedback is assuming increasingly im- portant role in quantum control and quantum information processing. In this work we analyze the application of such feedback techniques in eliminating decoherence in open quan- tum systems. In order to apply such system theoretic methods we first analyze the invariance properties of quadratic forms which corresponds to expected value of a measurement and present conditions for decouplability of measurement outputs of such time-varying open quantum systems from environmental effects.
Measurement and feedback control are essential features of quantum science, with applications ranging from quantum technology protocols to information-to-work conversion in quantum thermodynamics. Theoretical descriptions of feedback control are typically given in terms of stochastic equations requiring numerical solutions, or are limited to linear feedback protocols. Here we present a formalism for continuous quantum measurement and feedback, both linear and nonlinear. Our main result is a quantum Fokker-Planck master equation describing the joint dynamics of a quantum system and a detector with finite bandwidth. For fast measurements, we derive a Markovian master equation for the system alone, amenable to analytical treatment. We illustrate our formalism by investigating two basic information engines, one quantum and one classical.