Superradiant phase transition and statistical properties in the Dicke-Stark model
Phys. Rev. A 113, 033702 – Published 2 March, 2026
DOI: https://doi.org/10.1103/f5hk-95l2
Abstract
In this study we investigate the statistical properties and dynamical behaviors of the finite-size Dicke-Stark model. We numerically obtain the energy spectrum and eigenstates within the extended coherent-state space and subsequently utilize the quantum dressed master equation to describe the open-system dynamics under strong coupling. Under thermal equilibrium conditions, analyses of the negativity, zero-time-delay two-photon correlation function, and atom-spin-squeezing parameters reveal that as the coupling strength increases, the light field undergoes a transition from photon bunching to antibunching and then back to bunching. The Stark field can modulate both the extrema of the two-photon correlation function and their corresponding coupling strengths. At low temperatures, the system exhibits entanglement and spin squeezing. As the temperature increases, the entanglement gradually diminishes, while strong coupling facilitates the preservation of the entanglement. The atom-spin squeezing is highly sensitive to thermal fluctuations and vanishes rapidly with increasing temperature. Furthermore, we illustrate the time-evolution properties of the thermodynamic nonequilibrium of the system from a low-temperature state to a high-temperature state. Our results demonstrate that an appropriately tuned Stark interaction can effectively prolong the survival time of quantum entanglement against thermal noise. This work contributes to the fundamental understanding of quantum phenomena in Dicke-Stark systems.
