Electromagnetic-field-induced quenching of the effects of noisy lasers

Abstract

We demonstrate the possibility of quenching the effects of noisy lasers by intense coherent fields. For this purpose, we study the spectrum of resonance fluorescence from two-level atoms irradiated by bichromatic fields, where one field is coherent and the other stochastic. The spectrum is seen to be very sensitive to the frequencies of the two fields. In particular, we find a dramatic narrowing of the Rabi sidebands in the spectrum when the fluctuating field is tuned to the frequency of the Rabi sideband in the spectrum. We interpret the results in a dressed-state representation, revealing that the atom is sensitive to the fluctuating field, only when that field can induce resonant transitions between the dressed levels. Our calculation of the decay rates of the dressed levels predicts a narrowing of the sidebands by a factor of 4, when the driving field is broadband, while at the same time the central peak in the spectrum is broadened. Surprisingly, we find that there is the possibility of observing very narrow resonances even when noisy lasers interact with the atom.