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We investigate that no-knowledge measurement-based feedback control is utilized to obtain the estimation precision of the detection efficiency. For the feedback operators that concern us, no-knowledge measurement is the optimal way to…

Quantum Physics · Physics 2019-08-13 Dong Xie , Chunling Xu , Jianyong Chen , Anmin Wang

Various schemes have been proposed to overcome the drawback of the decoherence on quantum-enhanced parameter estimation. Here we suggest an alternative method, quantum feedback, to enhance the parameter precision of optimal quantum…

Quantum Physics · Physics 2015-06-24 Qiang Zheng , Li Ge , Yao Yao , Qi-jun Zhi

We theoretically study the quantum receivers with adaptive measurements feedback for discriminating quadrature amplitude modulation (QAM) coherent states in terms of average symbol error rate. For rectangular 16-QAM signal set, with…

Quantum Physics · Physics 2015-04-14 Tian Chen , Ke Li , Yuan Zuo , Bing Zhu

Quantum feedback control is a technology which can be used to drive a quantum system into a predetermined eigenstate. In this article, sufficient conditions for the experiment parameters of a quantum feedback control process of a homodyne…

Quantum Physics · Physics 2007-05-23 Andreas de Vries

Feedback is the core concept in cybernetics and its effective use has made great success in but not limited to the fields of engineering, biology, and computer science. When feedback is used to quantum systems, two major types of feedback…

Quantum Physics · Physics 2014-09-11 Bo Qi , Daoyi Dong , Chunlin Chen , Lijun Liu , Zairong Xi

We consider the task of estimating the randomly fluctuating phase of a continuous-wave beam of light. Using the theory of quantum parameter estimation, we show that this can be done more accurately when feedback is used (adaptive phase…

Quantum Physics · Physics 2009-11-10 D. T. Pope , H. M. Wiseman , N. K. Langford

A genuine feature of projective quantum measurements is that they inevitably alter the mean energy of the observed system if the measured quantity does not commute with the Hamiltonian. Compared to the classical case, Jacobs proved that…

Statistical Mechanics · Physics 2015-06-10 Kay Brandner , Michael Bauer , Michael T. Schmid , Udo Seifert

In quantum communication feedback may be defined in a number of distinct ways. An analysis of the effect feedback has on the rate information may be communicated is given, and a number of results and conjectures are stated.

Quantum Physics · Physics 2007-05-23 Garry Bowen

The thermodynamic uncertainty relation posits that higher thermodynamic costs are essential for a system to function with greater precision. Recent discussions have expanded thermodynamic uncertainty relations beyond classical…

Quantum Physics · Physics 2023-12-13 Yoshihiko Hasegawa

The laws of thermodynamics apply equally well to quantum systems as to classical systems, and because of this quantum effects do not change the fundamental thermodynamic efficiency of isothermal refrigerators or engines. We show that,…

Quantum Physics · Physics 2015-06-17 Jordan M. Horowitz , Kurt Jacobs

Communicating classical information with a quantum system involves the receiver making a measurement on the system so as to distinguish as well as possible the alphabet of states used by the sender. We consider the situation in which this…

Quantum Physics · Physics 2007-05-23 Kurt Jacobs

We describe a scheme for quantum error correction that employs feedback and weak measurement rather than the standard tools of projective measurement and fast controlled unitary gates. The advantage of this scheme over previous protocols…

Quantum Physics · Physics 2009-11-10 Mohan Sarovar , Charlene Ahn , Kurt Jacobs , Gerard J. Milburn

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…

Mesoscale and Nanoscale Physics · Physics 2016-08-31 Rusko Ruskov , Alexander N. Korotkov

Quantum mechanics establishes the ultimate limit to the scaling of the precision on any parameter, by iden- tifying optimal probe states and measurements. While this paradigm is, at least in principle, adequate for the metrology of quantum…

Quantum parameter estimation is central to many fields such as quantum computation, communications and metrology. Optimal estimation theory has been instrumental in achieving the best accuracy in quantum parameter estimation, which is…

Quantum Physics · Physics 2015-06-18 Shibdas Roy , Ian R. Petersen , Elanor H. Huntington

Quantum algorithms for diverse problems, including search and optimization problems, require the implementation of a reflection operator over a target state. Commonly, such reflections are approximately implemented using phase estimation.…

Quantum Physics · Physics 2018-03-08 Anirban Narayan Chowdhury , Yigit Subasi , Rolando D. Somma

It is widely accepted that the selection of measurement bases can affect the efficiency of quantum state estimation methods, precision of estimating an unknown state can be improved significantly by simply introduce a set of symmetrical…

Quantum Physics · Physics 2012-01-31 Chi Zhang , Guo-Yong Xiang , Yong-Sheng Zhang , Chuan-Feng Li , Guang-Can Guo

Quantum feedback control protocols can improve the operation of quantum devices. Here we examine the performance of a purification protocol when there are imperfections in the controls. The ideal feedback protocol produces an $x$ eigenstate…

Quantum Physics · Physics 2011-08-11 Joshua Combes , Howard M. Wiseman

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…

Mesoscale and Nanoscale Physics · Physics 2010-04-05 Qin Zhang , Rusko Ruskov , Alexander N. Korotkov

We discuss definitions of the quantum efficiency for binary-outcome qubit detectors with imperfect fidelity, focusing on the subclass of quantum non-demolition detectors. Quantum efficiency is analyzed for several models of detectors,…

Quantum Physics · Physics 2009-11-13 Alexander N. Korotkov
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