Quantum tunneling in the adiabatic Dicke model

被引:10
作者
Chen, Gang [1 ,2 ]
Chen, Zidong [1 ]
Liang, Jiuqing [2 ]
机构
[1] Shaoxing Coll Arts & Sci, Dept Phys, Shaoxing 312000, Peoples R China
[2] Shanxi Univ, Inst Theoret Phys, Taiyuan 030006, Peoples R China
来源
PHYSICAL REVIEW A | 2007年 / 76卷 / 04期
关键词
D O I
10.1103/PhysRevA.76.045801
中图分类号
O43 [光学];
学科分类号
070207 ; 0803 ;
摘要
The Dicke model describes N two-level atoms interacting with a single-mode bosonic field and exhibits a second-order phase transition from the normal to the superradiant phase. The energy levels are not degenerate in the normal phase but have degeneracy in the superradiant phase, where quantum tunneling occurs. By means of the Born-Oppenheimer approximation and the instanton method in quantum field theory, the tunneling splitting, inversely proportional to the tunneling rate for the adiabatic Dicke model, in the superradiant phase can be evaluated explicitly. It is shown that the tunneling splitting vanishes as exp(-N) for large N, whereas for small N it disappears as root N/exp(N). The dependence of the tunneling splitting on the relevant parameters, especially on the atom-field coupling strength, is also discussed.
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页数:4
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