How to observe and quantify quantum-discord states via correlations

Abstract

Quantum correlations between parts of a composite system most clearly reveal themselves through entanglement. Designing, maintaining, and controlling entangled systems is very demanding, which raises the stakes for understanding the efficacy of entanglement-free, yet quantum correlations, exemplified by quantum discord. Discord is defined via conditional mutual entropies of parts of a composite system and its direct measurement is hardly possible even via full tomographic characterization of the system state. Here we design a simple protocol to detect and quantify quantum discord in an unentangled bipartite system. Our protocol relies on a characteristic of discord that can be extracted from repeated direct measurements of certain correlations between subsystems of the bipartite system. The proposed protocol opens a way of extending experimental studies of discord to electronic systems, but can also be implemented in quantum-optical systems.

Publication DOI: https://doi.org/10.1103/PhysRevA.100.022321
Divisions: College of Engineering & Physical Sciences
Funding Information: This work was supported by the Leverhulme Trust Grants No. RPG-2016-044 (I.V.Y.), No. VP1-2015-005 (I.V.Y., Y.G.), the Italia-Israel project QUANTRA (Y.G.), and the DFG within the network CRC TR 183, C01 (Y.G.). The authors (I.V.L., I.V.Y., and Y.G.) are
Additional Information: © 2019 The American Physical Society
Uncontrolled Keywords: Atomic and Molecular Physics, and Optics
Publication ISSN: 1094-1622
Last Modified: 05 Feb 2024 08:43
Date Deposited: 02 Sep 2019 08:14
Full Text Link: https://arxiv.o ... /abs/1901.11514
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
https://journal ... RevA.100.022321 (Publisher URL)
PURE Output Type: Article
Published Date: 2019-08-16
Accepted Date: 2019-01-27
Authors: Hunt, Matthew A.
Lerner, Igor V.
Yurkevich, Igor V. (ORCID Profile 0000-0003-1447-8913)
Gefen, Yuval

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