Very long storage times and evaporative cooling of cesium atoms in a quasielectrostatic dipole trap

Engler, H.; Weber, T.; Mudrich, M.; Grimm, Rudolf; Weidemüller, Matthias

doi:10.1103/physreva.62.031402

Cited by 27 publications

(18 citation statements)

References 14 publications

(21 reference statements)

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“…In contrast to red-detuned dipole traps used for evaporation experiments [27,28], the spatial compression of the cold sample essentially results from gravity and is thus not aå ected when the optical potentials are ramped down. Moreover, many more atoms are initially loaded into the GOST as compared to typical red-detuned traps.…”

Section: Evaporative Coolingmentioning

confidence: 99%

Optical and evaporative cooling of caesium atoms in the gravito-optical surface trap

Hammes

Rychtarik

Druzhinina

et al. 2000

Journal of Modern Optics

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We report on cooling of an atomic caesium gas closely above an evanescent-wave atom mirror. At high densities, optical cooling based on inelastic re¯ections is found to be limited by a density-dependent excess temperature and trap loss due to ultracold collisions involving repulsive molecular states. Nevertheless, very good starting conditions for subsequent evaporative cooling are obtained. Our ® rst evaporation experiments show a temperature reduction from 10 mK down to 300 nK along with a gain in phasespace density of almost two orders of magnitude.

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Section: Evaporative Coolingmentioning

confidence: 99%

Optical and evaporative cooling of caesium atoms in the gravito-optical surface trap

Hammes

Rychtarik

Druzhinina

et al. 2000

Journal of Modern Optics

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“…As described in Refs. [25,26], the cesium atoms are loaded from a magnetooptical trap which is superimposed in the focus of the CO 2 laser. The MOT is operated in five-beam configuration and loads from a Zeeman slowed beam up to 10 8 particles at a density of 10 9 cm −3 as inferred from absorption imaging.…”

mentioning

confidence: 99%

“…The MOT is operated in five-beam configuration and loads from a Zeeman slowed beam up to 10 8 particles at a density of 10 9 cm −3 as inferred from absorption imaging. After turning of the magnetic field of the MOT a brief molasses cooling phase transfers about 5 × 10 5 atoms at a density of 5 × 10 11 cm −3 and a temperature of 40 µK into the optical dipole trap [25,26]. For the cold cesium atoms the CO 2 laser focus with its potential depth of 0.8 mK represents a harmonic trap with axial and radial trap frequencies of 12.8 Hz and 625 Hz respectively.…”

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confidence: 99%

Saturation ofCs2photoassociation in an optical dipole trap

Kraft¹,

Mudrich²,

Staudt³

et al. 2005

Phys. Rev. A

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We present studies of strong coupling in single-photon photoassociation of cesium dimers using an optical dipole trap. A thermodynamic model of the trap depletion dynamics is employed to extract absolute rate coefficents. From the dependence of the rate coefficient on the photoassociation laser intensity, we observe saturation of the photoassociation scattering probability at the unitarity limit in quantitative agreement with the theoretical model by Bohn and Julienne [1]. Also the corresponding power broadening of the resonance width is measured. We could not observe an intensity dependent light shift in contrast to findings for lithium and rubidium, which is attributed to the absence of a p or d-wave shape resonance in cesium.PACS numbers: 34.50. Rk,32.80.Pj Ultracold thermal and quantum degenerate atomic ensembles have allowed to investigate powerful coupling schemes between continuum scattering states of two atoms and bound molecular states of the corresponding dimer. Both photoassociation light [2,3] or magnetic field sweeps across Feshbach resonances [4,5,6] have lead to the formation of ultracold molecules. Three-body recombination of fermionic atoms near a Feshbach resonance has finally lead to the creation of molecular Bose Einstein condensates [7,8,9]. Recently, molecular photoassociation has been performed using a two-photon Raman process in a two-atom Mott insulator phase [10], which may prove to be a route to a molecular Mott insulator and, subsequently, an alternative way to a molecular BEC [11]. In contrast to this, the successful formation of ultacold molecular ensembles in the absolute rovibrational ground state, which is important if one wants to study molecular collisions and reactions over long interaction times, is still at large. Future routes for the production of absolute ground state molecules from a pair of atoms will certainly involve Raman type coupling schemes [12,13,14]. A very interesting approach to transfer highly vibrationally excited molecules into the vibrational ground state proposes the application of optimally controlled femtosecond laser pulses [15].In order to understand the regime of strong coupling in photoassociation, which is important for both continuous and femtosecond Raman processes, we report in this Rapid Communication investigations of saturation effects in the first photoassociation step from the two-atom continuum to an excited molecular level. This is also the determining step in the overall molecule formation rate [16]. Using an ultracold ensemble of cesium atoms trapped in a quasi-electrostatic optical trap [17] we are able to employ trap loss measurements to extract absolute photoassociation rate coefficients [18], from which the dependence of the rate coefficient on the photoassociation laser intensity is derived.

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“…The most noticeable ones include the trap loss and the finite lifetime of the dark states. For a long trap lifetime τ l ∼ 300 s [27,28], the probability of loss of atoms during the measurement time T is about ρ l ≈ 0.25/300; the uncertainty due to the trap loss is…”

Section: Sensitivity Of Magnetometermentioning

confidence: 99%