[2210.15693] Dynamic Phase Transitions in Periodically Driven Bardeen-Cooper-Schrieffer Systems

[Submitted on 27 Oct 2022]

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Overview: We present a systematic study of the dynamic phase diagram of a periodically driven BCS system as a function of driving strength and frequency. Three different driving mechanisms are considered and compared: an oscillating density of states, an oscillating pairing interaction, and an oscillating external pairing field. We identify trajectories in the parameter space of parametric resonances and four dynamic phases: Rabi-Higgs, Gapless, Synchronous Higgs, and Time Crystal. We show that the main features of the phase diagram are very robust to different driving protocols and discuss the order of transitions. By mapping the BCS problem to a collection of nonlinearly interacting classical oscillators, we shed light on the origin of the temporal crystal phases and parametric resonances that appear in subgap excitations.