Transmission of near-resonant light through a dense slab of cold atoms

Corman, Laura; Ville, Jean-Loup; Saint-Jalm, R.; Aidelsburger, Monika; Bienaimé, Tom; Nascimbène, Sylvain; Dalibard, Jean; Beugnon, Jérôme

doi:10.1103/physreva.96.053629

Cited by 74 publications

(76 citation statements)

References 48 publications

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“…The atomic cloud is optically extended (σ ≫ λ), so a simple refractive media treatment is adequate. It is dilute (nk −3 = 0.25), so dipole-dipole interatomic interactions [31,32] do not affect our experiment. To measure the force we apply a short pulse of duration τ p right after releasing the cloud, and image the momentum distribution after a long expansion time [18 ms, Figs.…”

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confidence: 99%

Observation of Optomechanical Strain in a Cold Atomic Cloud

et al. 2017

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We report the observation of optomechanical strain applied to thermal and quantum degenerate 87 Rb atomic clouds when illuminated by an intense, far detuned homogeneous laser beam. In this regime the atomic cloud acts as a lens which focuses the laser beam. As a backaction, the atoms experience a force opposite to the beam deflection, which depends on the atomic cloud density profile. We experimentally demonstrate the basic features of this force, distinguishing it from the well-established scattering and dipole forces. The observed strain saturates, ultimately limiting the momentum impulse that can be transferred to the atoms. This optomechanical force may effectively induce interparticle interactions, which can be optically tuned.Light-matter interactions are at the core of cold atom physics. A laser beam illuminating atoms close to atomic resonance frequency will apply a scattering force on them, and an inhomogeneous laser beam far from resonance will mainly apply an optical dipole force [1]. An intense, far detuned homogeneous laser beam does not exert a significant force on a single atom, though when applied on inhomogeneous atomic clouds, it will. This was pointed out [2] while studying lensing by cold atomic clouds in the context of nondestructive imaging.The atom's electric polarizability makes atomic clouds behave as refractive media with an index locally dependent on the cloud density. An atomic cloud thus behaves as a lens that can focus or defocus the laser beam. The atoms recoil in the opposite direction to the beam deflection due to momentum conservation. In solid lenses, this optomechanical force causes a small amount of stress with negligible strain, due to their rigidity. An atomic lens, however, deforms, making the force on the atoms observable by imaging their strain. We refer to this optomechanical force as electrostriction, since it resembles shape changes of materials under the application of a static electric field. Electrostriction can be viewed as an optically induced force between atoms, since the force each atom experiences depends on the local density of the other atoms.Optomechanical forces are applied in experiments on refractive matter mainly by optical tweezers, pioneered by [3], using structured light. Less commonly, such forces can be applied by homogeneous light using angular momentum conversion due to the material birefringence [4], or using structured refractive material shapes [5]. Optomechanical forces implemented by such techniques are used for optically translating and rotating small objects. By applying electrostriction on cold atoms we gain access to the effect of optical strain -an aspect in optomechanics not directly studied yet in spite of its importance in current research [6].Interactions between cold atoms can appear naturally or be externally induced and tuned. Tuning is mostly done using a magnetic Feshbach resonance, which was used to demonstrate many important physical effects such as Bose-Einstein condensate (BEC) collapse and explosion [7], Feshbach molecul...

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confidence: 99%

Observation of Optomechanical Strain in a Cold Atomic Cloud

et al. 2017

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“…Advances in experimental [1][2][3][4][5][6][7][8] and numerical [4,[9][10][11][12][13][14][15] techniques have revitalized classical electrodynamics of material samples as a topic of frontline research. The idea is that in cold, dense atomic samples dipole-dipole interactions between the atoms mediated by light may lead to cooperative behavior of light-matter systems, and even result in a strongly correlated sample.…”

Section: Introductionmentioning

confidence: 99%

Light propagation in systems involving two-dimensional atomic lattices

Javanainen

Rajapakse

2019

Phys. Rev. A

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We study the optical response of a 2D square lattice of atoms using classical electrodynamics. Due to dipole-dipole interactions, the lattice atoms polarize as if the lattice were an atom with up to three resonance frequencies, with cooperatively shifted resonances and altered transition linewidths. We show that when the distance between two 2D lattices is large enough and Bragg reflections are absent, the lattices interact among themselves as if they radiated a plane wave whose amplitude is in accordance with the radiation from a dipole moment continuously distributed in the lattice plane. We employ these results to study light propagation in stacks of 2D lattices, drawing on simple qualitative pictures of the response of a 2D lattice and light propagation in 1D waveguides. We show that a stack of 2D lattices may emulate regularly spaced atoms in a lossless 1D waveguide, and argue that in a suitable geometry the resonance shifts characteristic of 1D and 2D lattice structures may completely cancel to eliminate density dependent resonance shifts of atoms bound to a 3D lattice. A generalization to the case of anisotropic polarizability, such as in the presence of a magnetic field, reveals light frequencies induced by the magnetic field for which the lattice is either completely transparent, or completely opaque.

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“…Thus, FM spectroscopy measurements on strongly absorbing media are usually performed using thin penetration layers, such as in selective reflection spectroscopy [20], where measurements of collisional broadening [21,22] and atom-surface interaction have been reported [23,24]. In addition, cooperative atomic emissions have been investigated in dense atomic media, using both cold atomic gases [25][26][27][28][29][30][31] and hot atomic vapors [32][33][34]. In the latter, large absorption of the transmitted signal is avoided using nano-cells [35].…”

Section: Introductionmentioning

confidence: 99%

Large optical depth frequency modulation spectroscopy

et al. 2019

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Band-resolved frequency modulation spectroscopy is a common method to measure weak signals of radiative ensembles. When the optical depth of the medium is large, the signal drops exponentially and the technique becomes ineffective. In this situation, we show that a signal can be recovered when a larger modulation index is applied. Noticeably, this signal can be dominated by the natural linewidth of the resonance, regardless of the presence of inhomogeneous line broadening. We implement this technique on a cesium vapor, and then explore its main spectroscopic features. This work opens the road towards measurement of cooperative emission effects in bulk atomic ensemble.

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Transmission of near-resonant light through a dense slab of cold atoms

Cited by 74 publications

References 48 publications

Observation of Optomechanical Strain in a Cold Atomic Cloud

Observation of Optomechanical Strain in a Cold Atomic Cloud

Light propagation in systems involving two-dimensional atomic lattices

Large optical depth frequency modulation spectroscopy

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