Phase transition in the periodically pulsed Dicke model.

We study the effect of pulsed driving and kicked driving of the interaction term on the nonequilibrium phase transition in the Dicke model. Within the framework of Floquet theory, we observe the emergence of new nontrivial phases on impingement by such periodic pulses. Notably, our study reveals that a greater control over the dynamical quantum criticality is possible through the variation of multiple parameters related to the pulse, as opposed to a single parameter control in a monochromatic drive.

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Although we agree with the fact reported in García-Mata et al. [Phys. Rev.

Exploring chaos in the Dicke model using ground-state fidelity and Loschmidt echo.

We study the quantum critical behavior of the Dicke Hamiltonian with finite number of atoms and explore the signature of quantum chaos using measures like the ground-state fidelity and the Loschmidt echo and the time-averaged Loschmidt echo. We show that these quantities clearly point to the classically chaotic nature of the system in the superradiant (SR) phase. While the ground-state fidelity shows aperiodic oscillations as a function of the coupling strength, the echo shows aperiodic oscillations in time and decays rapidly when the system is in the SR phase.