Dynamics of coherence: Maximal quantum Fisher information versus Loschmidt echo

We consider the dynamics of maximal quantum Fisher information (MQFI) after sudden quenches for the one-dimensional transverse-field Ising model. Our results show, the same as Loschmidt echo, that there is a universality for the revival times, i.e., they do not depend on the initial state and the size of the quench and are given by integer multiples of T-rev similar or equal to N/2v(max), where N is the system size and v(max) is the maximal group velocity of quasiparticles. Critically enhanced and decreased at revival and decay times as T-rev T-dec are characterized by quenching from the order and disorder phases into the quantum phase transition, respectively, that can be utilized to detect the quantum critical point (QCP). In some quenches crossed from the QCP, nonanalytic behaviors appear at some times due to the turning of the local observable from one direction to another because of identifying the maximum value. We name this phenomenon the dynamical MQFI transitions, occurring at the critical times t(c). Interestingly, although no Fisher zero exists in the dynamics of MQFI, the first critical time emerged from the dynamical quantum phase transition is equal to the first time when the logarithm of MQFI is minimum. In addition, we unveil the long-time run of MQFI indicates a signature of a nonequilibrium quantum phase transition at the QCP. We also discuss the probability of the arising of macroscopic superpositions in the nonequilibrium dynamics of the system.