LAUSR

Using the Jordan–Wigner mean‐field (JW‐MF) approach, the dynamical quantum phase transition (DQPT) in the 1D spin‐1/2 XZZ model is studied, where the presence of the transverse magnetic field breaks the U(1) symmetry of the Hamiltonian and leads to loss of integrability. In the time evolution of the rate function, three kinds of behaviors will emerge: regular and irregular nonanalytic, and also regular analytic. Examples are given where the rate function shows the regular analytic can appear albeit a quench is crossed from a quantum critical point (QCP) and examples where the irregular nonanalyticity behaviors can arise in both quenching into the same phase and exceeded from a QCP. All the regular nonanalyticity behaviors at periodic instants t∗ happen when quenches cross from a QCP. In order to achieve a confirmation on our results, the long‐time average of the rate function is determined and show the occurrence of the nonequilibrium quantum phase transitions exactly at the QCPs and hence disclose the JW‐MF approach qualitatively works very well.