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We derive the form of the quantum filter equation describing the continuous observation of the phase of a quantum system in an arm of an interferometer via non-demolition measurements when the statistics of an input field used for the…

Quantum Physics · Physics 2016-01-19 John Gough

We consider the quantum computational process as viewed by an insider observer: this is equivalent to an isomorphism between the quantum computer and a quantum space, namely the fuzzy sphere. The result is the formulation of a reversible…

Quantum Physics · Physics 2007-05-23 Paola A. Zizzi

The purpose of this paper is to present a theoretic and numerical study of utilizing squeezing and phase shift in coherent feedback control of linear quantum optical systems. A quadrature representation with built-in phase shifters is…

Quantum Physics · Physics 2012-06-19 Guofeng Zhang , Heung Wing Joseph Lee , Bo Huang , Hu Zhang

We study several examples from quantum control theory in the framework of Wigner functions and measures for infinite dimensional open quantum systems. An axiomatic definition of coherent quantum feedback is proposed within this setting.

Mathematical Physics · Physics 2015-05-11 J. E. Gough , T. S. Ratiu , O. G. Smolyanov

This paper is devoted to analyzing the observer convergence rate for a class of linear control systems in a Hilbert space. To characterize the polynomial stability of the observer error system, we apply the spectral theory of linear…

Optimization and Control · Mathematics 2024-10-03 Alexander Zuyev , Julia Kalosha

We show how an initially prepared quantum state of a radiation mode in a cavity can be preserved for a long time using a feedback scheme based on the injection of appropriately prepared atoms. We present a feedback scheme both for optical…

Quantum Physics · Physics 2009-10-31 David Vitali , Paolo Tombesi , Gerard J. Milburn

The detection and quantification of quantum coherence play significant roles in quantum information processing. We present an efficient way of tomographic witnessing for both theoretical and experimental detection of coherence. We prove…

Quantum Physics · Physics 2021-05-13 Bang-Hai Wang , Si-Qi Zhou , Zhihao Ma , Shao-Ming Fei

Theoretical and experimental studies have suggested the relevance of quantum coherence to the performance of photovoltaic and light-harvesting complex molecular systems. However, there are ambiguities regarding the validity of statements we…

Chemical Physics · Physics 2022-08-31 Sahar Basiri-Esfahani , Farid Shahandeh

This brief survey analyzes the epistemological implications about the role of observer in the interpretations of Quantum Mechanics. As we know, the goal of most interpretations of quantum mechanics is to avoid the apparent intrusion of the…

General Physics · Physics 2008-11-25 Michele Caponigro

To control a quantum system via feedback, we generally have two options in choosing control scheme. One is the coherent feedback, which feeds the output field of the system, through a fully quantum device, back to manipulate the system…

Quantum Physics · Physics 2014-11-19 Naoki Yamamoto

Decoherence-free subspaces allow for the preparation of coherent and entangled qubits for quantum computing. Decoherence can be dramatically reduced, yet dissipation is an integral part of the scheme in generating stable qubits and…

Quantum Physics · Physics 2009-11-07 Ben Tregenna , Almut Beige , Peter L. Knight

Making quantum mechanical equations and concepts come to life through interactive simulation and visualization are commonplace for augmenting learning and teaching. However, graphical visualizations nearly always exhibit a set of hard-coded…

Conditional measurements on the undriven mode of a two-mode cavity QED system prepare a coherent superposition of ground states which generate quantum beats. The continuous system drive induces decoherence through the phase interruptions…

Coherent control, aka quantum control, is a central concept in quantum computing that is attracting increasing attention from both the quantum foundations and quantum software communities. Defining coherent control in the presence of…

Logic in Computer Science · Computer Science 2026-03-02 Kathleen Barsse , Romain Péchoux , Simon Perdrix

On the example of a quantum oscillator the connection of the dynamical coherent state with the phase symmetry breaking and the existence of the nondissipative motion is considered. In multiparticle systems of interacting particles similar…

Quantum Physics · Physics 2024-08-13 Yu. M. Poluektov

This article may be seen as a summary and a final discussion of the work that the author has done in recent years on the foundation of quantum theory. It is shown that quantum mechanics as a model follows under certain specific conditions…

Quantum Physics · Physics 2022-12-21 Inge S. Helland

In a previous paper (arXiv:1008.3661v1[quant-ph] 21 Aug 2010), we have given a purely logical proof of the Conway and Kochen Free Will theorem in QM: the freedom of the observer implies the freedom of the observed particle. Here we show…

Quantum Physics · Physics 2010-10-20 Iegor Reznikoff

Simultaneous decoherence of conjugate observables of an open quantum system leads to a classical statistical mechanical description with constant phase space probability density in terms of a uniform ensemble. We investigate a scenario…

Quantum Physics · Physics 2026-03-30 S. Adarsh , P. N. Bala Subramanian , Sreeraj T. P

Coherent feedback is a non-measurement based, hence a back-action free, method of control for quantum systems. A typical application of this control scheme is squeezing enhancement, a purely non-classical effect in quantum optics. In this…

Quantum Physics · Physics 2016-11-17 Sanae Iida , Mitsuyoshi Yukawa , Hidehiro Yonezawa , Naoki Yamamoto , Akira Furusawa

I review basic principles of the quantum mechanical measurement process in view of their implications for a quantum theory of general relativity. It turns out that a clock as an external classical device associated with the observer plays…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Robert Oeckl