原子-原子相互作用影响下Dicke模型的量子相变

Quantum Phase Transition for the Dicke Model with the Atom-Atom Interaction

原子与光腔相互作用的动力学特性的研究一直是量子光学研究的热点,本文利用自旋相干态变换和基态变分法从理论上求解光腔中冷原子系统的基态能量表达式,并且给出丰富的基态相图。在正常相时给出基态能量稳定值的解析解;而超辐射相时,我们可以利用迭代的方法近似得到原子布居数、平均光子数和基态能量随原子-场耦合强度的变化。本文主要呈现出原子-原子相互作用强度改变正常相到超辐射相的量子相变点,且是一阶相变,但未出现新的量子相和量子相变。

The research about dynamic characteristics of the interaction between the atoms and the optical cavity has been a hot content in quantum optics.By means of the spin coherentstate transformations and the ground state variational method,we theoretically presented the expressions of ground state energy of the system,in which the cold atoms interact with the optical cavity,as well as the rich ground state phase diagram.The analytical solution of the ground state was obtained in normal phase.The scaled atomic population,the mean photon number and the ground state energy were revealed by adjusting the collective atom-field coupling strength with the iterative method in the superradiant phase.This paper mainly points out that the atom-atom interaction strength can change the quantum phase transition point（from the normal phase to the superradiant phase）,which is the one-order phase transition,but does not lead to the emergence of a new quantum phase and quantum phase transiton.