Response of macroscopic and microscopic dynamical quantifiers to the quantum critical region

Abstract

At finite temperatures, the quantum critical region (QCR) emerges as a consequence of the interplay between thermal and quantum fluctuations. We seek suitable physical quantities, which during dynamics can give prominent response to QCR in the transverse field quantum XY model. We report that the maximum energy absorbed, the nearest neighbor entanglement, and the quantum mutual information of the time-evolved state after a quench of the transverse magnetic field exhibit a faster drop with temperature when the initial magnetic field is taken from within the QCR, compared to the choice of the initial point from different phases. We propose a class of dynamical quantifiers, originating from the response of these physical quantities and show that they can faithfully mimic the equilibrium physics, namely detection of the QCR at finite temperatures.