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:2002.05840 · Physical Review A

Noise-adaptive test of quantum correlations with quasiprobability functions

Seung-Woo Lee, Jaewan Kim, Wonmin Son

Published Jul 7, 2020• 2 citations
arXivHTMLPDF

Abstract

We introduce a method for testing quantum correlations in terms of quasiprobability functions in the presence of noise. We analyze the effects of measurement imperfection and thermal environment on quantum correlations and show that their noise effects can be well encapsulated into the change of the order parameter of the generalized quasiprobability function. We then formulate a noise-adaptive entanglement witness in the form of a Bell-type inequality by using the generalized quasiprobability function. Remarkably, it allows us to observe quantum correlations under severe noise. Our method provides a useful tool to test quantum correlations in near-term noisy quantum processors with continuous-variable systems.

DOI
10.1103/physreva.102.012408

Related papers

Testing quantum nonlocality by generalized quasiprobability functions

Seung-Woo Lee, Hyunseok Jeong, Dieter Jaksch

We derive a Bell inequality based on a generalized quasiprobability function, which is parametrized by one nonpositive real value. Two types of known Bell inequalities formulated in terms of the Wigner and the $Q$ functions are included as limiting cases. We investigate violations of our Bell inequalities for single-photon entangled states and two-mode squeezed vacuum states when varying the detector efficiency. We show that the Bell inequality for the $Q$ function allows the lowest detection efficiency for violations of local realism.

arXiv:0908.0541•Physical Review A•Aug 4, 2009•30 citations

Test of Nonlocality for a Continuous-Variable State Based on an Arbitrary Number of Measurement Outcomes

Wonmin Son, Časlav Brukner, M. S. Kim

We propose a scheme to test Bell's inequalities for an arbitrary number of measurement outcomes on entangled continuous-variable (CV) states. The Bell correlation functions are expressible in terms of phase-space quasiprobability functions with complex ordering parameters, which can experimentally be determined via a local CV-qubit interaction. We demonstrate that CV systems can give higher violations of these Bell's inequalities than of the ones developed for two-outcome observables.

arXiv:quant-ph/0602119•Physical Review Letters•Sep 11, 2006•17 citations

Entanglement detection via the condition of quantum correlation

Che‐Ming Li, Li-Yi Hsu, Yueh-Nan Chen +2 more

We develop a necessary condition of quantum correlation. It is utilized to construct a $d$-level bipartite Bell-type inequality which is strongly resistant to noise and requires only analyses of $O(d)$ measurement outcomes compared to the previous result $O({d}^{2})$. Remarkably, a connection between the arbitrary high-dimensional bipartite Bell-type inequality and entanglement witnesses is found. Through the necessary condition of quantum correlation, we propose that the witness operators to detect truly multipartite entanglement for a generalized Greenberger-Horne-Zeilinger (GHZ) state with two local measurement settings and a four-qubit singlet state with three settings. Moreover, we also propose a robust entanglement witness to detect a four-level tripartite GHZ state with only two local measurement settings.

arXiv:0709.1982•Physical Review A•Sep 12, 2007•3 citations

Evolution of quantum correlation undergoing decoherence using the information entropy inequality

Xia Liu, Huai-Xin Lu, Jia-Qiang Zhao +3 more

Using the information-theoretic inequality proposed by Braunstein and Caves, we study the evolution of quantum correlation in the presence of different noisy channels. First, we experimentally prepare the high-fidelity two-bit entangled state and simulated the bit-flip and phase-shift noise using an all-optical experimental setup. Then, we study the quantum correlation evolution of a two-bit entangled system using the information difference of entropy under different noisy channels and noisy environments. It is found that the quantum correlation degradation depends on the type of noise and noisy channels. Our work provides a new essential tool for quantum information processing and measurement, and offers new insight into the evolution of quantum correlation in open systems.

Laser Physics Letters•Nov 7, 2018•1 citation

Entanglement verification of noisy NOON states

Martin Bohmann, Jan Sperling, W. Vogel

Entangled quantum states, such as NOON states, are of major importance for quantum technologies due to their quantum-enhanced performance. At the same time, their quantum correlations are relatively vulnerable when they are subjected to imperfections. Therefore, it is crucial to determine under which circumstances their distinct quantum features can be exploited. In this paper, we study the entanglement property of noisy NOON states. This class of states is a generalization of NOON states including various attenuation effects, such as mixing, constant or fluctuating losses, and dephasing. To verify their entanglement, we pursue two strategies: detection-based entanglement witnesses and entanglement quasiprobabilities. Both methods result from our solution of so-called separability eigenvalue equations. In particular, the entanglement quasiprobabilities allow for a full entanglement characterization. As examples of our general treatment, the cases of NOON states subjected to Gaussian dephasing and fluctuating atmospheric losses are explicitly studied. In any correlated fluctuating loss channel, entanglement is found to survive for nonzero transmissivity. In addition, an extension of our approach to multipartite systems is given, and the relation to the quantum-optical nonclassicality in phase space is discussed.

arXiv:1704.05637•Physical Review A•Jul 17, 2017•12 citations

Continuous Variables Quantum Information in Noisy Environments

Adriano Berni, Ulrik L. Andersen

The technological progress of the last few decades has brought us the ability of exploiting quantum effects to accomplish a variety of relevant tasks. Yet, quantum phenomena are fragile, and with the ability to engineer quantum information protocols comes the problem of keeping such information safe from the detrimental effects of noise and losses. In the present work we investigate continuous variables Gaussian quantum information in noisy environments, studying the effects of various noise sources in the cases of a quantum metrological task, an error correction scheme and discord-type correlations. We engage each of the topics from a theoretical point of view, successively delving into the details of the experimental realizations and concluding with a survey of the results. In particular, we present experimental implementation of an ab initio, deterministic, real-time adaptive phase estimation protocol in a realistic thermalized scenario, we investigate the performance of an error correction scheme for elimination of correlated noise in a quantum channel, and we study the robustness of discord-type quantum correlations when subject to additive noise and attenuation.

•Jan 1, 2014•0 citations
We introduce a method for testing quantum correlations in terms of quasiprobability functions in the presence of noise. We analyze the effects of measurement imperfection and thermal environment on quantum correlations and show that their noise effects can be well encapsulated into the change of the order parameter of the generalized quasiprobability function. We then formulate a noise-adaptive entanglement witness in the form of a Bell-type inequality by using the generalized quasiprobability function. Remarkably, it allows us to observe quantum correlations under severe noise. Our method provides a useful tool to test quantum correlations in near-term noisy quantum processors with continuous-variable systems.
We derive a Bell inequality based on a generalized quasiprobability function, which is parametrized by one nonpositive real value. Two types of known Bell inequalities formulated in terms of the Wigner and the QQQ functions are included as limiting cases. We investigate violations of our Bell inequalities for single-photon entangled states and two-mode squeezed vacuum states when varying the detector efficiency. We show that the Bell inequality for the QQQ function allows the lowest detection efficiency for violations of local realism.
We develop a necessary condition of quantum correlation. It is utilized to construct a ddd-level bipartite Bell-type inequality which is strongly resistant to noise and requires only analyses of O(d)O(d)O(d) measurement outcomes compared to the previous result O(d2)O({d}^{2})O(d2). Remarkably, a connection between the arbitrary high-dimensional bipartite Bell-type inequality and entanglement witnesses is found. Through the necessary condition of quantum correlation, we propose that the witness operators to detect truly multipartite entanglement for a generalized Greenberger-Horne-Zeilinger (GHZ) state with two local measurement settings and a four-qubit singlet state with three settings. Moreover, we also propose a robust entanglement witness to detect a four-level tripartite GHZ state with only two local measurement settings.
Using the information-theoretic inequality proposed by Braunstein and Caves, we study the evolution of quantum correlation in the presence of different noisy channels. First, we experimentally prepare the high-fidelity two-bit entangled state and simulated the bit-flip and phase-shift noise using an all-optical experimental setup. Then, we study the quantum correlation evolution of a two-bit entangled system using the information difference of entropy under different noisy channels and noisy environments. It is found that the quantum correlation degradation depends on the type of noise and noisy channels. Our work provides a new essential tool for quantum information processing and measurement, and offers new insight into the evolution of quantum correlation in open systems.
Entangled quantum states, such as NOON states, are of major importance for quantum technologies due to their quantum-enhanced performance. At the same time, their quantum correlations are relatively vulnerable when they are subjected to imperfections. Therefore, it is crucial to determine under which circumstances their distinct quantum features can be exploited. In this paper, we study the entanglement property of noisy NOON states. This class of states is a generalization of NOON states including various attenuation effects, such as mixing, constant or fluctuating losses, and dephasing. To verify their entanglement, we pursue two strategies: detection-based entanglement witnesses and entanglement quasiprobabilities. Both methods result from our solution of so-called separability eigenvalue equations. In particular, the entanglement quasiprobabilities allow for a full entanglement characterization. As examples of our general treatment, the cases of NOON states subjected to Gaussian dephasing and fluctuating atmospheric losses are explicitly studied. In any correlated fluctuating loss channel, entanglement is found to survive for nonzero transmissivity. In addition, an extension of our approach to multipartite systems is given, and the relation to the quantum-optical nonclassicality in phase space is discussed.
The technological progress of the last few decades has brought us the ability of exploiting quantum effects to accomplish a variety of relevant tasks. Yet, quantum phenomena are fragile, and with the ability to engineer quantum information protocols comes the problem of keeping such information safe from the detrimental effects of noise and losses. In the present work we investigate continuous variables Gaussian quantum information in noisy environments, studying the effects of various noise sources in the cases of a quantum metrological task, an error correction scheme and discord-type correlations. We engage each of the topics from a theoretical point of view, successively delving into the details of the experimental realizations and concluding with a survey of the results. In particular, we present experimental implementation of an ab initio, deterministic, real-time adaptive phase estimation protocol in a realistic thermalized scenario, we investigate the performance of an error correction scheme for elimination of correlated noise in a quantum channel, and we study the robustness of discord-type quantum correlations when subject to additive noise and attenuation.