Quantum discord in a spin-1/2 transverseXYchain following a quench

Abstract

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