Cooperative effects in light-atom interaction
|Achieving Dicke superradiance in the optical domain and in vacuum is challenging because of the large required spatial atomic density. One releases this constraint, placing atoms in a high finesse cavity such that a bouncing photon can interact many times with the atomic ensemble. We noticed that the cavity was not necessary as far as the medium as a large optical density (OD), and it is coherently excited by a laser . We gave an original interpretation of the flash effect in this phenomenon. Then, we cast light on the richness of the flash effect, and the key role of the interference between the incident laser and the forward emission. Interference can enhance [superflash, see figure (a)] or suppress the flash , generate cooperative pulse emission [see figure (b)] , and lead to precise two-photon measurement in Λ-scheme . We also used the flash effect to extract the elastic scattering component in highly saturated medium , proposed a sensitive FM-spectroscopy method , and calculated the first-order correction due to near-field effects .|
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