Survival of time-evolved correlations depends on whether quenching is across critical point in XY spin chain

TL;DR

This paper investigates how quantum correlations evolve over time in an XY spin chain after sudden parameter changes, revealing that crossing the critical point enhances correlations, while staying within the same phase has different effects.

Contribution

It provides a detailed analysis of the dynamics of quantum correlations during quenches across and within phases in the XY spin chain, including finite temperature effects.

Findings

Enhanced bipartite correlations when quenching from ordered to disordered phase.

Correlations are suppressed when quenching from disordered to ordered phase at zero temperature.

Thermal fluctuations influence the evolution of quantum correlations.

Abstract

The time-dynamics of quantum correlations in the quantum transverse anisotropic XY spin chain of infinite length is studied at zero as well as finite temperatures. The evolution occurs due to the instantaneous quenching of the coupling constant between the nearest-neighbor spins of the model, which is either performed within the same phase or across the quantum phase transition point connecting the order-disorder phases of the model. We characterize the time-evolved quantum correlations, entanglement and quantum discord, which exhibit varying behavior depending on the initial state and the quenching scheme. We show that the system is endowed with enhanced bipartite quantum correlations compared to that of the initial state, when quenched from ordered to the deep disordered phase. However, bipartite quantum correlations are almost washed out when the system is quenched from disordered to the ordered phase with the initial state being at the zero-temperature. Moreover, we identify the condition for the occurrence of enhanced bipartite correlations when the system is quenched within the same phase. Finally, we investigate the bipartite quantum correlations when the initial state is a thermal equilibrium state with finite temperature which reveals the effects of thermal fluctuation on the phenomena observed at zero-temperature.