Loschmidt amplitude zeros as a probe for criticality in the quenched XY model

Abstract

This paper investigates the correspondence between dynamical phase transitions (DPT) and quenches across quantum critical points (QCP) in ground state quenches of a spin-1/2 XY model. These DPTs are identified by treating the wavefunction overlap between pre- and post-quench states as a partition funtion and determining its Fisher zeros. It is found that DPTs do not always occur when the quench crosses a quantum critical line. A general condition for the occurrence of these DPTs in the XY model is derived.