Quantum Discord in a spin-1/2 transverse XY Chain Following a Quench

TL;DR

This paper investigates how quantum discord and other correlations evolve in a spin-1/2 transverse XY chain after a quench, revealing non-monotonic behavior, scaling laws, and differences from entanglement measures.

Contribution

It provides a detailed analysis of quantum discord dynamics post-quench, highlighting its peak at intermediate quenching rates and its scaling behavior near critical points.

Findings

Quantum discord vanishes at very slow and very fast quenching rates.

Discord exhibits a peak at an intermediate quenching rate.

Discord scales with the quenching rate following a power law in slow quenching regimes.

Abstract

We report a study on the zero-temperature quantum discord as a measure of two-spin correlation of a transverse XY spin chain following a quench across a quantum critical point and investigate the behavior of mutual information, classical correlations and hence of discord in the final state as a function of the rate of quenching. We show that though discord vanishes in the limit of very slow as well as very fast quenching, it exhibits a peak for an intermediate value of the quenching rate. We show that though discord and also the mutual information exhibit a similar behavior with respect to the quenching rate to that of concurrence or negativity following an identical quenching, there are quantitative differences. Our studies indicate that like concurrence, discord also exhibits a power law scaling with the rate of quenching in the limit of slow quenching though it may not be expressible in a closed power law form. We also explore the behavior of discord on quenching linearly across a quantum multicritical point (MCP) and observe a scaling similar to that of the defect density.