Measuring quantumness: from theory to observability in interferometric setups

TL;DR

This paper introduces an experimentally measurable quantumness measure based on the incompatibility of quantum states, which detects quantum correlations and acts as a universal witness for quantum discord using interferometric setups.

Contribution

It proposes a novel quantumness measure linked to state incompatibility, implementable via interferometry, and capable of detecting quantum discord and non-classical correlations.

Findings

The measure can be experimentally implemented with interferometry.

It detects one-way quantum correlations in bipartite systems.

It serves as an efficient universal witness for quantum discord.

Abstract

We investigate the notion of quantumness based on the non-commutativity of the algebra of observables and introduce a measure of quantumness based on the mutual incompatibility of quantum states. We show that such a quantity can be experimentally measured with an interferometric setup and that, when an arbitrary bipartition of a given composite system is introduced, it detects the one-way quantum correlations restricted to one of the two subsystems. We finally show that, by combining only two projective measurements and carrying out the interference procedure, our measure becomes an efficient universal witness of quantum discord and non-classical correlations.