Zhu Hanjie, Zhang Guofeng, Fan Heng
Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), School of Physics and Nuclear Energy Engineering; and State Key Laboratory of Software Development Environment, Beihang University, Xueyuan Road No. 37, Beijing 100191, China.
State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China.
Sci Rep. 2016 Jan 20;6:19751. doi: 10.1038/srep19751.
The biased Dicke model describes a system of biased two-level atoms coupled to a bosonic field, and is expected to produce new phenomena that are not present in the original Dicke model. In this paper, we study the critical properties of the biased Dicke model in the classical oscillator limits. For the finite-biased case in this limit, We present analytical results demonstrating that the excitation energy does not vanish for arbitrary coupling. This indicates that the second order phase transition is avoided in the biased Dicke model, which contrasts to the original Dicke model. We also analyze the squeezing and the entanglement in the ground state, and find that a finite bias will strongly modify their behaviors in the vicinity of the critical coupling point.
有偏狄克模型描述了一个与玻色场耦合的有偏二能级原子系统，预计会产生原始狄克模型中不存在的新现象。在本文中，我们研究了经典振子极限下有偏狄克模型的临界性质。对于该极限下的有限偏置情况，我们给出了分析结果，表明对于任意耦合，激发能都不会消失。这表明有偏狄克模型中避免了二级相变，这与原始狄克模型形成对比。我们还分析了基态中的压缩和纠缠，发现有限偏置会在临界耦合点附近强烈改变它们的行为。
