Nonlinear Dynamics In The Cavity Quantum Electrodynamics System Under The Ultrastrong Coupling

The interaction between the single-model light field and the atom has always been an important subject of quantum optics.By using the rotating-wave approximation?RWA?,a series of important results have been obtained in the weak coupling and strong coupling regimes.The effects predicted by quantum mechanics,such as single-photon source,quantum entanglement and photon blockade,have been reached experimentally.Moreover,as the research goes deep,studies on the light-atom interaction have been extended the deep strong coupling?DSC?regime in recent years.But the method of RWA is not appropriate in here.The behaviors of atoms and light field also show some different characters from the case of RWA.We thus need to use new theoretical method to study the system in the DSC regime.This paper mainly studies the dynamics of the system that consists of a single-model field interacting with a three-level atom in the DSC regime.The contents include the following four parts:?1?We give the briefly discussion of the dynamic behaviors and characteristics of a two level atom interaction with a single-mode cavity in weak coupling,strong coupling and DSC regimes,respectively.?2?We investigate the dynamics of the system that consists of a three-level atom deep strongly coupled a single-model cavity.We find that the population of the cavity field in Fock space displays a periodic behavior in the limit?₀/??0,where?₀??? are atom?cavity?frequency.Meanwhile,the maximum spatial value of the photon number distribution is proportional to the coupling strength.However,with the increase of atomic frequency this periodic behavior disappeared gradually.?3?In order to study the dynamics of the system in the phase space,we plot the Wigner function to show the evolution of the multi-component coherent states of the cavity field.In the limit?₀/??0,the Wigner function is a coherent state with three components.Particularly,the central components remain unchanged and the components of the two sides rotate around the central component during the process of movement.As the atomic frequency increases,there is interference between the three components of the coherent state,but the center of the middle component still does not move.The reason for this behavior is that the three eigenstates of the three level system lead to the evolution of the coherent states of multi-components.