Comparison of different measures for quantum discord under non-Markovian noise

TL;DR

This paper compares different geometric and original measures of quantum discord under non-Markovian noise, revealing their similarities, differences, and sudden transition points, which could help preserve quantum correlations.

Contribution

It provides a comparative analysis of geometric and original quantum discord measures under non-Markovian noise, highlighting their dynamic behaviors and critical transition points.

Findings

Quantum discord and one geometric measure remain constant under non-Markovian dephasing for a finite time.

All three measures exhibit a common sudden change point during evolution.

The study's insights could aid in maintaining quantum correlations over time.

Abstract

Two geometric measures for quantum discord were recently proposed by Modi et al. [Phys. Rev. Lett. 104, 080501 (2010)] and Dakic et al. [Phys. Rev. Lett. 105, 190502 (2010)]. We study the similarities and differences for total quantum correlations of Bell-diagonal states using these two geometry-based quantum discord and the original quantum discord. We show that, under non-Markovian dephasing channels, quantum discord and one of the geometric measures stay constant for a finite amount of time, but not the other geometric measure. However, all the three measures share a common sudden change point. Our study on critical point of sudden transition might be useful for keeping long time total quantum correlations under decoherence.