Collective suppression of optical hyperfine pumping in dense clouds of atoms in microtraps

Abstract

We observe a density-dependent collective suppression of optical pumping between the hyperfine ground states in an array of submicrometer-sized clouds of dense and cold rubidium atoms. The suppressed Raman transition rate can be explained by strong resonant dipole-dipole interactions that are enhanced by increasing atom density, and are already significant at densities of 0.1k 3 , where k denotes the resonance wavenumber. The observations are consistent with stochastic electrodynamics simulations that incorporate the effects of population transfer via internal atomic levels embedded in a coupled-dipole model.

Quantum and nonlinear effects in light transmitted through planar atomic arrays

“…An appealing feature of light scattering from cold atoms [39][40][41][42][43][44][45][46][47][48][49][50] is that light-mediated strong DD interactions can establish correlations between atoms at fluctuating positions, which are most simply described using atomic field operators for the ground and excited statesψ g;e ðrÞ. Hence, hP þ ðrÞi ¼ hψ These in turn depend on three-body correlations, etc., resulting in a hierarchy of equations of motion for correlation functions 51,52 .…”

“…Note the relatively small number of equations 2N compared to the full quantum system size 2 N . This formalism has been applied to the modeling of pumping of atoms in dense clouds 50 , and has also been extended to cavity quantum electrodynamics (QED) 57 . Spatially correlated scattering between different atoms is accounted for in Eqs.…”

Comparison of three approaches to light scattering by dilute cold atomic ensembles

“…This approach has already been used to explain recent experiments on the collective reduction of the radiation pressure force [15,24], on off-axis scattering by very elongated clouds [16], and might also explain the effect reported in Ref. [25]. In this work we analyze the applicability of this method in a wide range of parameters -scattering angles, frequencies of the probe light, optical depths of the clouds.…”

Subradiance-protected excitation spreading in the generation of collimated photon emission from an atomic array

“…Collective optical interactions in cold trapped atomic ensembles, where systems with increasing densities can now be achieved, are being actively studied experimentally [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Since the light-mediated resonant dipoledipole interactions depend on the average atomic separation, the close proximity of the atoms can lead to a correlated optical response [15,16] that no longer obeys continuous medium descriptions of electrodynamics [17,18].…”