Quantum tunneling in the adiabatic Dicke model
- Department of Physics, Shaoxing College of Arts and Sciences, Shaoxing 312000 (China)
- Institute of Theoretical Physics, Shanxi University, Taiyuan 030006 (China)
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 {radical}(N)/exp(N). The dependence of the tunneling splitting on the relevant parameters, especially on the atom-field coupling strength, is also discussed.
- OSTI ID:
- 21020856
- Journal Information:
- Physical Review. A, Vol. 76, Issue 4; Other Information: DOI: 10.1103/PhysRevA.76.045801; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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