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


Proceedings of the 34th Samahang Pisika ng Pilipinas Physics Congress, University of the Philippines Visayas, Iloilo City, 18–21 Aug 2016, SPP-2016-5C-06.


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.