The power of quantum channels for creating quantum correlations

TL;DR

This paper investigates how local quantum channels can generate quantum correlations from classically correlated states, introducing a new measure and analyzing the channels' power in creating such correlations.

Contribution

It introduces a computable measure for quantum correlations based on non-commutativity and analyzes the power of local channels in generating quantum correlations.

Findings

Quantum correlations produced are proportional to initial classical correlations.

The power of a channel is obtained by averaging over all initial states.

The measure is compared with the geometrical measure for specific states.

Abstract

Local noise can produce quantum correlations on an initially classically correlated state, provided that it is not represented by a unital or semi-classical channel \cite{DagmarBruss}. We find the power of any given local channel for producing quantum correlations on an initially classically correlated state. We introduce a computable measure for quantifying the quantum correlations in quantum-classical states, which is based on the non-commutativity of ensemble states in one party of the composite system. Using this measure we show that the amount of quantum correlations produced, is proportional to the classical correlations in the initial state. The power of an arbitrary channel for producing quantum correlations is found by averaging over all possible initial states. Finally we compare our measure with the geometrical measure of quantumness for a subclass of quantum-classical sates, for which we have been able to find a closed analytical expression.