How to observe and quantify quantum-discorded 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.
Keywords
Cite
@article{arxiv.1907.08130,
title = {How to observe and quantify quantum-discorded states via correlations},
author = {Matthew A. Hunt and Igor V. Lerner and Igor V. Yurkevich and Yuval Gefen},
journal= {arXiv preprint arXiv:1907.08130},
year = {2019}
}
Comments
10 pages, 9 figures. arXiv admin note: substantial text overlap with arXiv:1901.11514