Quantum phase transition of nonlocal Ising chain with transverse field   in a resonator
  We study the quantum phase transition in a spin chain with variable Ising interaction and position-dependent coupling to a resonator field. Such a complicated model, usually not present in natural physical systems, can be simulated by an array of qubits based on man-made devices and exhibits interesting behavior. We show that, when the coupling between the qubit and field is strong enough, a super-radiant phase transition occurs, and it is possible to pick a particular field mode to undergo this phase transition by properly modulating the strength of the Ising interaction. We also study the impact of the resonator field on the magnetic properties of the spin chain, and find a rich set of phases characterized by distinctive qubit correlation functions. 
Yu-Na Zhang, Xi-Wang Luo, Guang-Can Guo, Zheng-Wei Zhou, and Xingxiang   Zhou
quant-ph