Probing the system’s dynamics around dynamical quantum phase transitions

Dynamical quantum phase transitions (DQPTs) are defined by the non-analyticity intime in the Loschmidt echo, which measures the overlap between the time-evolvedstate and the initial state when a system is brought out of equilibrium. While the studyof DQPTs has been thriving, how the system behaves around the critical time remainsan open question.

In this talk, we will explore the dynamics of the many-body systemsaround DQPT using various probes. We find that the extrema in the time evolutionof the equilibrium order parameter are connected to DQPTs in the Su-SchreifferHeeger model. We will also discuss how the correlations spread under the influence ofinter and intra- cell interactions in the model as probed by unequal time Greenfunctions.

The concept of Loschmidt amplitude spectrum – an extension of theLoschmidt echo measures will also be introduced. The spectrum suggests there is apopulation redistribution in the momentum space across the transition in thequantum Ising model, providing us new insight into the behaviour of the systemaround DQPTs.