Super quantum discord for a class of two-qubit states with weak measurement

TL;DR

This paper derives explicit formulas for super quantum discord in a broader class of two-qubit states and explores how it behaves under decoherence, showing it decreases with measurement strength.

Contribution

It provides the first explicit expressions for super quantum discord for a 4-parameter family of two-qubit states, extending previous results beyond Bell-diagonal states.

Findings

Weak measurements reveal more quantum correlations than strong measurements.

Super quantum discord decreases monotonically with measurement strength under decoherence.

Explicit formulas enable better understanding of quantum correlations in complex states.

Abstract

So far, super quantum discord has been calculated explicitly only for Bell-diagonal states and expressions for more general quantum states are not known. In this paper, we derive explicit expressions for super quantum discord for a larger class of two-qubit states, namely, a 4-parameter family of two-qubit states. We observe that, weak measurements obtain more quantumness of correlations than strong measurements. As an application, the dynamic behavior of the super quantum discord under decoherence channel is investigated. We find that, the super quantum discord decreases monotonically as a function of the measurement strength parameter.