Physics Seminar of the School of Physical Sciences
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Dynamical Quantum Phase Transitions and Topological Order Parameter
Date: November 7, 2017 (Tuesday)
Abstract: The physics of quantum phase transitions and corresponding universality class are well studied. Recently, there has been a proposal of a novel non-equilibrium quantum phase transition occurring in the real time evolution of a closed quantum system following a sudden quench or a slow ramp. Corresponding non-analyticities are manifested at different instants of real time in the so-called `Loschmidt echo' (or the rate function of the return probability). At these instants, the lines of Fisher (Yang-Lee) zeros cross the real time axis. Starting from the basics of quantum phase transitions in models under consideration, we shall show how these dynamical phase transitions emerge. Interestingly, these transitions are characterized by a topological order parameter that exhibits a distinct jump of unit magnitude marking each dynamical transition.