Kinetic Theory for Transverse Optomechanical Instabilities

Tesio, Enrico; Robb, G. R. M.; Ackemann, T.; Firth, W. J.; Oppo, Gian-Luca

doi:10.1103/physrevlett.112.043901

Cited by 31 publications

(67 citation statements)

References 32 publications

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“…Interactions are also tuned by optical Feshbach resonance [17], optical cavities [18], or radio frequency Feshbach resonance [19]. Interactions can be induced by shining a laser beam on the atoms and creating a feedback mechanism to their response by an externally pumped cavity or a half cavity [20][21][22][23][24][25]. The electrostriction force reported here is a new kind of induced force between atoms, and may be useful in cold atoms and quantum degenerate atom experiments.…”

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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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“…As the lattice is self-organized and not externally imposed, it is not rigid but can have dynamics leading to the possibility to study the propagation of coupled light-density perturbations, correlations of fluctuations in the light and density modes, and, in presence of atomic coherence, corresponding features in quantum transport. The mechanism of self-structuring with optical feedback described here is expected to apply also to the electron density in a plasma in the presence of ponderomotive forces 28 , to 'soft matter' formed from dielectric beads 22,23 , and deformable membranes 29 . Beside periodic patterns, one emerging feature suggested by theoretical simulations is the possibility of localized, soliton-like, density-light structures (single or multiple holes in the density), which can be set and erased by external control pulses and sustained by homogeneous driving only 30 .…”

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confidence: 89%

Optomechanical self-structuring in a cold atomic gas

et al. 2014

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The rapidly developing field of optomechanics aims at the com- bined control of optical and mechanical modes1–3. In cold atoms, the spontaneous emergence of spatial structures due to opto- mechanical back-action has been observed in one dimension in optical cavities3–8 or highly anisotropic samples9. Extensions to higher dimensions that aim to exploit multimode configurations have been suggested theoretically10–16. Here, we describe a simple experiment with many spatial degrees of freedom, in which two continuous symmetries—rotation and translation in the plane orthogonal to a pump beam axis—are spontaneously broken. We observe the simultaneous long- range spatial structuring (with hexagonal symmetry) of the density of a cold atomic cloud and of the pump optical field, with adjustable length scale. Being based on coherent phenom- ena (diffraction and the dipole force), this scheme can poten- tially be extended to quantum degenerate gases

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“…However, in the limit N → ∞ the dynamics of the gas can, for sufficiently short times be reliably approximated by a Vlasov equation (in 1D) [18,19] …”

Section: Modelmentioning

confidence: 99%

Atomic self-ordering in a ring cavity with counterpropagating pump fields

Ostermann

Grießer

Ritsch

2015

EPL

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The collective dynamics of mobile scatterers and light in optical resonators generates complex behaviour. For strong transverse illumination a phase transition from homogeneous to crystalline particle order appears. In contrast, a gas inside a single-side pumped ring cavity exhibits an instability towards bunching and collective acceleration called collective atomic recoil lasing (CARL). We demonstrate that by driving two orthogonally polarized counter propagating modes of a ring resonator one realises both cases within one system. The corresponding phase diagram depending on the two pump intensities exhibits regions in which either a generalized form of self-ordering towards a travelling density wave with constant centre of mass velocity or a CARL instability is formed. Controlling the cavity driving then allows to accelerate or slow down and trap a sufficiently dense beam of linearly polarizable particles.

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Kinetic Theory for Transverse Optomechanical Instabilities

Cited by 31 publications

References 32 publications

Observation of Optomechanical Strain in a Cold Atomic Cloud

Observation of Optomechanical Strain in a Cold Atomic Cloud

Optomechanical self-structuring in a cold atomic gas

Atomic self-ordering in a ring cavity with counterpropagating pump fields

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