光腔内一维扩展玻色-哈伯德模型的量子相变

Quantum phase transitions of one-dimensional extended Bose-Hubbard model in an optial cavity

光晶格为研究冷原子提供了一个非常纯净并且容易调节的实验平台.在光腔内的光晶格中载入冷原子,可以引入光子原子之间的耦合相互作用,有助于人们研究超辐射转变以及超流和超固体等量子相.除了最近邻格点之间原子排斥相互作用有助于形成超固体以外,原子光子耦合系数的正负符号随位置交替变化也有助于形成超固体.本文将这两种相互作用都考虑进光腔中扩展玻色-哈伯德模型,通过测量原子密度、光子密度、超流序参量、固体序参量和超固体序参量,用平均场方法得到系统的基态相图,发现与硬核系统相比,软核系统的超固体范围更大更容易被发现.此研究结果有助于指导光腔中冷原子实验寻找新的量子相.

The optical lattice provides a very clean and controllable experimental platform for the study of cold atoms.The loading of cold atoms on the optical lattice in an optical cavity is able to introduce the coupling interaction between photons and atoms,which helps us to study the superradiant transition and the quantum phases such as superfluid and supersolid.Besides the supersolid drived by the nearest-neighbor interactions,the positive and negative signs of the atom-photon coupling alternate with the position and they could also lead to the supersolid.In this paper,two kinds of interactions are considered in the BoseHubbard model in an optical cavity,and the ground state phase-diagram is obtained by mean-field method through measuring the atomic density,photon density,the superfluid order parameter,solid order parameter and supersolid order parameter.Compared with the hard-core system,the supersolid of the soft-core system emerges in a larger range and is easier to be found.The results of our study are helpful to guide the cold atom experiment in a cavity to search for new quantum phases.