Experimental investigation of classical and quantum correlations under decoherence

TL;DR

This paper experimentally studies how classical and quantum correlations evolve under decoherence in an optical setup, revealing sudden changes and instances where quantum correlations surpass classical ones, impacting quantum information processing.

Contribution

It provides the first experimental observation of the dynamics of bipartite correlations under decoherence, including the dominance of quantum over classical correlations.

Findings

Sudden change in correlation decay rates.

Quantum correlation can be larger than classical correlation.

Correlations show immunity against certain decoherence types.

Abstract

It is well known that many operations in quantum information processing depend largely on a special kind of quantum correlation, that is, entanglement. However, there are also quantum tasks that display the quantum advantage without entanglement. Distinguishing classical and quantum correlations in quantum systems is therefore of both fundamental and practical importance. In consideration of the unavoidable interaction between correlated systems and the environment, understanding the dynamics of correlations would stimulate great interest. In this study, we investigate the dynamics of different kinds of bipartite correlations in an all-optical experimental setup. The sudden change in behaviour in the decay rates of correlations and their immunity against certain decoherences are shown. Moreover, quantum correlation is observed to be larger than classical correlation, which disproves the early conjecture that classical correlation is always greater than quantum correlation. Our observations may be important for quantum information processing.