| Searching for supersolids and exploring their properties has always been a hot issue in the study of condensed matter physics.At present,there are four main hosts that can be used to study supersolids:solid ~4He,electrons in lattice,cold atoms,and photons.In the past ten years,the successful control of the interaction strength and dimensionality of ultra-cold quantum gas has made it possible to explore many interesting physical phenomena.For example,the phase transition from superfluid phase to Mott-Insulator phase is observed in ultra-cold quantum gas.Therefore,the controllable ultra-cold atom system in the lattice provides an original and convenient platform to achieve this goal.In addition to solid ~4He and cold atom systems,due to the advantages of artificial controllability and no need for cooling of circuit quantum electrodynamics,its light quantum system has gradually become an application platform for realizing supersolids.This article focuses on the possible existence of supersolid of light in light quantum systems.Supersolid is an interesting macroscopic performance of quantum mechanics,with spontaneously formed crystal structure and non-diagonal long-range order that characterizes superfluidity.The extended Jaynes-Cummings-Hubbard model,which describes circuitquantum electrodynamics system,is theoretically simulated by using large-scale worm quantum Monte Carlo method.The ground state phase diagram is studied to find whether there is stable supersolid phase of light in various geometric lattice structures.A new kind of supersolid of light has been discovered in triangular lattice,in which three characteristics of superradiation,superfluid and solid orders coexist.In one-dimensional and square lattices,a first-order phase transition occurs between the superfluid phase and the solid phase,so there is no stable supersolid of light,confirming the previous supersolid of light given by Bujnowski et al.[Phys.Rev.A 90,043801(2014)]is not stable.Interestingly,soliton/beats of the local densities arise if the chemical potential is adjusted in the finite-size chain.However,this soliton-superfluid coexistence can not be considered as a supersolid in the thermodynamic limit.In the triangular lattice,through measurement of the structural factor,momentum distribution and superflfluid stiffffness for various system sizes,we found that a superradiant supersolid of light exists on triangular lattices due to the antiferromagnetic correlation between photons via light-atom coupling and this area is less than the regional average field results.The phase transition between our superradiant supersolid phase and the superradiant solid phase can be continuous(first order)and above(below)the“symmetry point”,which is different from the pure Bose-Hubbard model on the triangular lattice.The results of this paper are helpful for the search of new superradiant supersolid phases of light in circuit quantum electrodynamics experiments and other light-matter coupling systems. |
