Analytic solutions for degenerate Raman-coupled model
Zhang Zhi-Ming(张智明)† and Yu Ya-Fei(於亚飞)
Laboratory of Photonic Information Technology, School of Information and Photoelectronic Science & Engineering, South China Normal University, Guangzhou 510006, China
Abstract The Raman-coupled interaction between an atom and a single mode of a cavity field is studied. For the cases in which a light field is initially in a coherent state and in a thermal state separately, we have derived the analytic expressions for the time evolutions of atomic population difference , modulus of the Bloch vector, and entropy . We find that the time evolutions of these quantities are periodic with a period of . The maxima of and appear at the scaled interaction time points . At these time points, , which shows that the atom and the field are not entangled. Between these time points, , which means that the atom and the field are entangled. When the field is initially in a coherent state, near the maxima, the envelope of is a Gaussian function with a variance of ( is the mean number of photons). Under the envelope, oscillates at a frequency of . When the field is initially in a thermal state, near the maxima, is a Lorentz function with a width of .
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