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

Physical Review A

Quantum measurement apparatus with a squeezed reservoir: Control of decoherence and nonlocality in phase space

Matthias Jakob, Yonatan Abranyos, János A. Bergou

Published Nov 8, 2001• 10 citations
Publisher

Abstract

We propose a quantum measurement model where the environment is taken to be a squeezed reservoir. This kind of meter-environment coupling has a dramatic influence on the decoherence rate. Depending on the phase and the squeezing parameter the decoherence time can be enhanced or reduced arbitrarily. We derive the Wigner function for the system-meter state, and discuss its nonclassical features. Further, we test quantum nonlocality in phase space on the basis of coincidence measurements of the entangled system-meter scheme, and investigate the effect of a highly reduced decoherence rate. Surprisingly, in sharp contrast to popular notion, violations of the Bell inequality can be observed even when the meter has reached a macroscopic state.

DOI
10.1103/physreva.64.062102

Related papers

A Quantum Dynamical Mode for the Control of Decoherence

HuangWan-Xia, WangQin-Mou

We present a quantum measurement model where the meter is taken to be a squeezed reservoir. We realize decoherence in macroscopic limits using Bogoliubov transformation, and this kind of system-meter coupling has a dramatic influence on decoherence.

理论物理通讯：英文版•Jan 1, 2005•0 citations

A Quantum Dynamical Mode for the Control of Decoherence

Huang Wan-Xia, Wang Qin-mou

We present a quantum measurement model where the meter is taken to be a squeezed reservoir. We realize decoherence in macroscopic limits using Bogoliubov transformation, and this kind of system-meter coupling has a dramatic influence on decoherence.

Communications in Theoretical Physics•Jan 1, 2005•0 citations

Degree of entanglement in a quantum-measurement process

Matthias Jakob, Yonatan Abranyos, János A. Bergou

We suggest a quantum-measurement model in an ion trap that specifies the probability distribution of two distinct internal ground states of a trapped four-level ion. The external degrees of motion of the four-level ion constitute the meter that, in turn, is coupled to the environment by engineered reservoirs. In a previous publication, a similar measurement model was employed to test decoherence effects on quantum nonlocality in phase space on the basis of coincidence measurements of the entangled system-meter scheme. Here, we study the effects of decoherence on the entanglement of formation characterized by the concurrence. The concurrence of the system enables us to find the maximum possible violation of the Bell inequality. Surprisingly, this model gives illustrative insights into the question as to what extent the Bell inequality can be considered as a measure of entanglement.

arXiv:quant-ph/0204054•Physical Review A•Aug 27, 2002•11 citations

A Quantum Dynamical Mode for the Control of Decoherence Using a Squeezed Reservoir

Maosheng Wang

In this paper,we deduce a decoherence term of a quantum dynamical mode using the characteristics of squeezed operators and coherent states,and realize decoherence in macroscopic limits,then we find this kind of system-meter coupling has a dramatic influence on decoherence.

Journal of Anhui Normal University•Jan 1, 2006•0 citations

Testing Quantum Nonlocality in Phase Space

Konrad Banaszek, Krzysztof Wódkiewicz

We propose an experimental scheme for testing nonlocality of a correlated two-mode quantum state of light. We show that the correlation functions violating the Bell inequalities in the proposed experiment are equal to the joint two-mode $Q$ function and the Wigner function. This assigns a novel operational meaning to these two quasidistribution functions in tests of quantum nonlocality and also establishes a direct relationship between two intriguing aspects of quantum mechanics: the nonlocality of entangled states and the noncommutativity of quantum observables, which underlies the nonclassical structure of the phase-space quasidistribution functions.

arXiv:quant-ph/9806068•Physical Review Letters•Mar 8, 1999•338 citations

Nonlocality of the Schrödinger cat

Krzysztof Wódkiewicz

The nonlocality of the Schrödinger cat is established. A correlation measurement that exhibits quantum interference in the form of the Wigner function of the cat state is introduced. The relation of this correlation to quantum interference in phase space and the nonlocal character of the Schrödinger cat are discussed. It is shown that the Schrödinger cat correlation function leads to violation of the Bell inequality for macroscopically distinguishable states of the cat.

New Journal of Physics•Sep 12, 2000•30 citations
We propose a quantum measurement model where the environment is taken to be a squeezed reservoir. This kind of meter-environment coupling has a dramatic influence on the decoherence rate. Depending on the phase and the squeezing parameter the decoherence time can be enhanced or reduced arbitrarily. We derive the Wigner function for the system-meter state, and discuss its nonclassical features. Further, we test quantum nonlocality in phase space on the basis of coincidence measurements of the entangled system-meter scheme, and investigate the effect of a highly reduced decoherence rate. Surprisingly, in sharp contrast to popular notion, violations of the Bell inequality can be observed even when the meter has reached a macroscopic state.
We suggest a quantum-measurement model in an ion trap that specifies the probability distribution of two distinct internal ground states of a trapped four-level ion. The external degrees of motion of the four-level ion constitute the meter that, in turn, is coupled to the environment by engineered reservoirs. In a previous publication, a similar measurement model was employed to test decoherence effects on quantum nonlocality in phase space on the basis of coincidence measurements of the entangled system-meter scheme. Here, we study the effects of decoherence on the entanglement of formation characterized by the concurrence. The concurrence of the system enables us to find the maximum possible violation of the Bell inequality. Surprisingly, this model gives illustrative insights into the question as to what extent the Bell inequality can be considered as a measure of entanglement.
We propose an experimental scheme for testing nonlocality of a correlated two-mode quantum state of light. We show that the correlation functions violating the Bell inequalities in the proposed experiment are equal to the joint two-mode QQQ function and the Wigner function. This assigns a novel operational meaning to these two quasidistribution functions in tests of quantum nonlocality and also establishes a direct relationship between two intriguing aspects of quantum mechanics: the nonlocality of entangled states and the noncommutativity of quantum observables, which underlies the nonclassical structure of the phase-space quasidistribution functions.