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Register a new userCoherent Backscattering with Nonlinear Atomic Scatterers
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We study coherent backscattering of a quasi-monochromatic laser by a dilute gas of cold two-level atoms. We consider the perturbative regime of weak intensities, where nonlinear effects arise from {em inelastic} two-photon scattering processes. Here, coherent backscattering can be formed by interference between {em three} different scattering amplitudes. Consequently, if elastically scattered photons are filtered out from the photodetection signal by means of suitable frequency-selective detection, we find the nonlinear backscattering enhancement factor to exceed the linear barrier two.
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Light propagating in an optically thick sample experiences multiple scattering. It is now known that interferences alter this propagation, leading to an enhanced backscattering, a manifestation of weak localization of light in such diffuse samples. This phenomenon has been extensively studied with classical scatterers. In this letter we report the first experimental evidence for coherent backscattering of light in a laser-cooled gas of Rubidium atoms.
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