Non-equilibrium dynamics of superconductivity in the Hatsugai-Kohmoto model

We study the non-equilibrium dynamics of the superconducting order parameter in the Hatsugai-Kohmoto (HK) model. In the absence of superconductivity, its ground state is a non-Fermi liquid, whose properties are controlled by the HK interaction. Our protocol involves quantum quenching the HK interaction but leaving the interaction responsible for superconductivity unchanged. We map out the non-equilibrium dynamical phase diagram of the interacting model which contains three phases where, at long times, the order parameter amplitude vanishes, approaches a constant value or persistently oscillates. We also investigate the Loschmidt echo in searching for dynamical quantum phase transition, and find no significant correlation between the three phases and the non-analytic temporal behaviour of the Loschmidt echo. The momentum space entanglement entropy between positive and negative momentum modes, relevant for Coopair pairing, is calculated. Counterintuitively, this momentum space entanglement does not change significantly during the quench dynamics and its value remains reasonably large even for vanishing superconducting order parameter. Nevertheless, its derivative with respect to the HK interaction signals the dynamical phase transition associated to the late time vanishing of superconductivity.
Comment: 10 pages, 8 figures