Quantum coherence assisted dynamical phase transition

Abstract: Quantum coherence will undoubtedly play a fundamental role in understanding the dynamics of quantum many-body systems, thereby to reveal its genuine contribution is of great importance. In this paper, we specialize our discussions on the one-dimensional transverse field quantum Ising model initialized in the coherent Gibbs state, and investigate the effects of quantum coherence on dynamical phase transition (DQPT). After quenching the strength of the transverse field, the effects of quantum coherence are studied by Fisher zeros, rate function and winding number. We find that quantum coherence not only recovers the traditional DQPT related to quantum phase transition, but also generates some entirely new DQPTs which are independent of equilibrium quantum critical point. In these entirely new QDPTs, the line of Fisher zeros cuts the imaginary axis twice, i.e., there are two critical modes, one makes the winding number jump down but another makes it jump up. We also find that the rate function can not be used to describe DQPT at high temperature, because the critical mode no longer dominates. This work sheds new light on the fundamental connection between quantum critical phenomena and quantum coherence.