Quantum Correlations Relativity for Continuous Variable Systems

TL;DR

This paper demonstrates that the amount of non-classical correlations, such as quantum discord, in continuous variable systems depends on the choice of degrees of freedom, highlighting the relativity of quantum correlations.

Contribution

It introduces the concept of quantum correlations relativity, showing that non-classical correlations vary with different degrees of freedom in bipartite continuous variable systems.

Findings

Quantum discord depends on the choice of degrees of freedom.

Non-classical correlations are ubiquitous in continuous variable systems.

Quantum correlations can be zero in one basis and non-zero in another.

Abstract

It is shown that a choice of degrees of freedom of a bipartite continuous variable system determines amount of non-classical correlations (quantified by discord) in the system's state. Non-classical correlations (that include entanglement as a special kind of correlations) are ubiquitous for such systems. For a quantum state, if there are not non-classical correlations (quantum discord is zero) for one, there are in general non-classical correlations (quantum discord is non-zero) for another set of the composite system's degrees of freedom. The physical relevance of this 'quantum correlations relativity' is emphasized also in the more general context.