Fingerprint of chaos and quantum scars in kicked Dicke model: An out-of-time-order correlator study

TL;DR

This study uses out-of-time-order correlators to diagnose chaos and quantum scars in a kicked Dicke model, linking classical chaos indicators with quantum dynamics and experimental relevance.

Contribution

It introduces OTOC as a tool to detect chaos and quantum scars in the kicked Dicke model, connecting classical and quantum chaos indicators.

Findings

OTOC growth rate captures Lyapunov exponent in chaotic regimes.

Saturation value of OTOC indicates onset of chaos.

Quantum scars identified via OTOC dynamics.

Abstract

We investigate the onset of chaos in a periodically kicked Dicke model (KDM), using the out-of-time-order correlator (OTOC) as a diagnostic tool, in both the oscillator and the spin subspaces. In the large spin limit, the classical Hamiltonian map is constructed, which allows us to investigate the corresponding phase space dynamics and to compute the Lyapunov exponent. We show that the growth rate of the OTOC for the canonically conjugate coordinates of the oscillator is able to capture the Lyapunov exponent in the chaotic regime. The onset of chaos is further investigated using the saturation value of the OTOC, that can serve as an alternate indicator of chaos in a generic interacting quantum system. This is also supported by a system independent effective random matrix model. We further identify the quantum scars in KDM and detect their dynamical signature by using the OTOC dynamics. The relevance of the present study in the context of ongoing cold atom experiments is also discussed.