Quenching Dynamics and Quantum Information

TL;DR

This paper reviews how quantum correlations like entanglement and discord evolve in spin chains after quenches through critical points, highlighting their scaling behavior and effects of interactions.

Contribution

It provides a comparative analysis of entanglement and discord scaling in quenched spin chains and extends the study to include three-spin interactions and decoherence effects.

Findings

Quantum discord and concurrence behave similarly during quenches.

Both quantities scale with defect density in the final state.

Quantum discord's behavior is qualitatively similar to decoherence factors.

Abstract

We review recent studies on the measures of zero temperature quantum correlations namely, the quantum entanglement (concurrence) and discord present in the final state of a transverse XY spin chain following a quench through quantum critical points; the aim of these studies is to explore the scaling of the above quantities as a function of the quench rate. A comparative study between the concurrence and the quantum discord shows that their behavior is qualitatively the same though there are quantitative differences. For the present model, the scaling of both the quantities are given by the scaling of the density of the defect present in the final state though one can not find a closed form expression for the discord. We also extend our study of quantum discord to a transverse Ising chain in the presence of a three spin interaction. Finally, we present a study of the dynamical evolution of quantum discord and concurrence when two central qubits, initially prepared in a Werner state, are coupled to the environmental XY spin chain which is driven through quantum critical points. The qualitative behavior of quantum discord and concurrence are found to be similar as that of the decoherence factor.