T-C模型的多稳态和Dicke相变  

Multiple Stable States and Dicke Phase Transition of T-C Model

作　　者：刘妮[1] 凌铭霞 崔新林[1] 梁九卿[1] LIU Ni;LING Ming-xia;CUIXin-lin;LIANG Jiu-qing(Institute of Theoretical Physics,Shanxi University,Taiyuan 030006,China)

机构地区：[1]山西大学理论物理研究所,山西太原030006

出　　处：《量子光学学报》2021年第2期87-93,共7页Journal of Quantum Optics

基　　金：国家自然科学基金(11772177,12047571):山西省高等学校科技创新项目(2019L0069);山西省“1331工程”重点学科建设计划。

摘　　要：本文用相干态变分法研究了旋波近似下单模光腔中两个二能级原子多稳态和Dikce相变。首先我们得到系统的本征态和本征能量,并通过变分求解不同的光子数解和边界条件。通过调节参数,多重稳定态等丰富相图被呈现,系统除了正常相到超辐射相的量子相变,还出现一组分原子反转的正常态到受激辐射态的相变,而两组分原子都反转的正常态在全空间稳定存在。In this paper, the multiple stable states and Dicke phase transition of two two-level atoms in a single mode optical cavity are studied by using the coherent state variational method in the rotating wave approximation. There is no interaction between two atoms for the distance. Firstly, we obtain the eigenstates and eigenenergies of the system,meanwhile, we solve different photon number solutions and boundary conditions by variational method. Figure 1 gives the the limit case that the second atom does not exist and T-C model degrades into J-C model, in which a second-order Dicke quantum phase transition from the normal phase to the superadiant phase occurs. Meanwhile, the completely reversed atomic population exists with the increase of the atom-field coupling strength. The effects of the detuning between the cavity’s frequency and the atomic frequencies on Dicke phase transition are characterized by numerical calculation. Rich phase diagrams are presented by adjusting the parameters, such as the atom-field coupling strengths, the frequency detuning and the non-equilibrium parameter. These phase diagrams visually show Dicke phase transitions. Interestingly, multi-stable excited states are induced by the atomic inversion. Apart from Dicke phase transition from normal phase to superradiant phase, the system shows a new phase transition from the revised normal state by just one atom to stimulated radiation state, while the completely revised normal state by both atoms exists stably in the whole space. In addition, the application of J-C model or T-C model in quantum optics generally considers the driven field, which can at least make the critical quantum phase point or boundary shift. In the future we can add the driven field in Hamiltonian and discuss the effect on Dicke phase transition.

关 键 词：T-C模型 Dicke相变 相干态变分法 反转的辐射态 

分 类 号：O431[机械工程—光学工程]