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arXiv · 1901.11514

How to observe and quantify quantum-discorded states

Matthew A. Hunt·Igor V. Lerner·Igor V. Yurkevich·Yuval Gefen
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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 quantum discord and characterize a discorded state in an unentangled bipartite system. Our protocol is based on an electronic setup and relies on a characteristic of discord that can be extracted from repeated direct measurements of current correlations between subsystems. The proposed protocol opens a way of extending experimental studies of discord to many-body condensed matter systems.

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Matthew A. Hunt, Igor V. Lerner, Igor V. Yurkevich, Yuval Gefen. 2019-01-31. How to observe and quantify quantum-discorded states. https://doi.org/10.1103/physreva.100.022321

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