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Counter-Rotating Transition Mediated Coherent Effects in Spontaneous Emission in a Three-Level Atom

The coherent effects including counter-rotating coupling on spontaneous emission are presented for a microwave driven V-type three-level atom. Novel coherent effects are realized: (i) There is an infinite series of spectral lines, which are separated by the microwave frequency, independent of the separation of the excited states, no matter whether the microwave transition is resonant or not. This is in sharp contrast to the case of the weak coupling, where the spectral interval is mainly determined by the separation of the excited states. (ii) Selective appearance and inhibition of the spectral lines are obtained simply by varying the microwave Rabi frequency. (iii) Spectral lines have a twofold structure. The physical mechanisms are analysed by employing the dressed states representation.