Photoassociation of Ultracold Atoms: A New Spectroscopic Technique

Stwalley, William C.; Wang, He

doi:10.1006/jmsp.1999.7838

Cited by 246 publications

(169 citation statements)

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“…Photoassociation (PA) of ultracold atoms has been a remarkably useful tool for determining scattering lengths characterizing ultracold atom collisions, for producing ultracold molecules, and for providing extremely precise measurements of atomic radiative lifetimes (see Refs. [1,2] for reviews). This utility is largely a consequence of the spectroscopic precision afforded by the small thermal broadening in a laser or evaporatively cooled gas.…”

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confidence: 99%

“…The v 0 83 level was chosen for its large ratio of the photoassociation rate to the rate of offresonant scattering from the atomic resonance. Photoassociation can be detected because it causes a reduction in atom number when excited molecules spontaneously decay into pairs of hot atoms that escape the trap [1,2]. The number of atoms remaining following the PA pulse is determined by polarization phase-contrast imaging [24], and compared with a ''background'' measurement of the number of atoms without the PA pulse.…”

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Intensity Dependence of Photoassociation in a Quantum Degenerate Atomic Gas

et al. 2003

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We have measured the intensity dependent rate and frequency shift of a photoassociation transition in a quantum degenerate gas of 7 Li. The rate increases linearly with photoassociation laser intensity for low intensities, whereas saturation is observed at higher intensities. The measured rates and shifts agree reasonably well with theory within the estimated systematic uncertainties. Several theoretically predicted saturation mechanisms are discussed, but a theory in which saturation arises because of quantum mechanical unitarity agrees well with the data. DOI: 10.1103/PhysRevLett.91.080402 PACS numbers: 03.75.Nt, 33.20.Kf, 33.70.-w, 34.20.Cf Photoassociation (PA) of ultracold atoms has been a remarkably useful tool for determining scattering lengths characterizing ultracold atom collisions, for producing ultracold molecules, and for providing extremely precise measurements of atomic radiative lifetimes (see Refs. [1,2] for reviews). This utility is largely a consequence of the spectroscopic precision afforded by the small thermal broadening in a laser or evaporatively cooled gas. Quantum degenerate gases are especially interesting because the coherence of the atomic field may enable the formation of a molecular Bose-Einstein condensate (BEC) from an atomic one by coherent Raman transitions [3,4], stimulated Raman adiabatic passage [5], or by other coherent adiabatic population transfer schemes [6,7].There have been extensive theoretical studies of the rate of PA [8][9][10][11][12]. The rate is predicted to increase linearly with intensity at low intensities, while various mechanisms have been proposed that cause saturation of the rate at higher intensities. Among these mechanisms are the quantum mechanical unitarity limit on the rate of atomic collisions [11], a breakdown of the two-mode approximation [4,13] for PA of Bose condensates caused by coupling to noncondensed atomic modes [12,14 -16], and the depletion of the atomic pair correlation function [15]. Photoassociation resonances are also predicted to exhibit a spectral shift proportional to the light intensity caused by coupling to the continuum of free-atom states [11,[17][18][19]. In contrast to theory, there are relatively few experimental measurements, and only two that could be considered ''precise'' (which we define as measurements with uncertainties of less than a factor of 2). We previously measured the spectral light shift using quantum degenerate 7 Li and obtained good agreement with theory [20]. Both the spectral shift and the PA rate constant were recently measured in a Na condensate, and good agreement with two-body theory was found [21]. Saturation was not observed in this experiment. Saturation was observed in two other lower precision experiments [22,23], but these experiments were performed in a magneto-optical trap, where the temperatures were greater than 100 K and the corresponding unitaritylimited rates were quite small, of the order of 1 s ÿ1 or less.We report precise measurements of both the rate of PA and the spectral shift in...

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Intensity Dependence of Photoassociation in a Quantum Degenerate Atomic Gas

et al. 2003

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“…2 Ultra-low-energy collisions are particularly topical because of recent experiments involving atoms and ions in traps, and there is great interest in the properties of ultracold molecules produced either by buffergas cooling 3 or by photoassociation of atoms in a Bose condensate. 4 Properties such as scattering lengths and densities of states near dissociation can be strongly influenced by the potential at very long range. It is thus quite important to use potential energy functions that have the correct asymptotic behavior.…”

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On the long-range and short-range behavior of potentials from reproducing kernel Hilbert space interpolation

Soldán

Hutson

2000

The Journal of Chemical Physics

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

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“…Long-range states of neutral diatomic molecules are important in many contexts, including the photoassociation of laser-cooled atoms; 4 this is particularly topical because of the recent observation of photoassociation in a Bose-Einstein condensate, producing ultracold molecules in states near dissociation. 5 There have been a number of previous experimental investigations of the Ne 2 ϩ ion, principally in its ground electronic state, as listed in Table I 9 7.42 Ϯ0.16 cm Ϫ1 , is probably the more reliable because they observed many more vibrational levels.…”

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Microwave electronic spectrum of the Ne⋯Ne+ long-range complex: The interaction potential

Carrington

Gammie

Page

et al. 2002

The Journal of Chemical Physics

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. The full interaction potential between Ne( 1 S) and Ne ϩ ( 2 P) is determined by least-squares fitting of potential parameters to spectroscopic data, principally from the near-dissociation microwave spectra of the Ne 2 ϩ complex. The potential obtained in this way incorporates the potential curves for all six electronic states correlating with Ne( 1 S)ϩNe ϩ ( 2 P) and the couplings between them. Coupled-channel calculations on the potential take account of breakdown of the Born-Oppenheimer approximation and provide an accurate description of the microwave rovibronic spectrum involving levels within ϳ10 cm Ϫ1 of the first dissociation limit. The Ne 2 ϩ ions are both vibrationally and rotationally hot: the spectrum involves levels up to at least Jϭ25/2 and there is evidence for transitions involving levels near the second dissociation limit. The long-range levels involved have ͗r͘ up to 12 Å, compared with an equilibrium bond length of 1.756 Å for the ground electronic state. The long-range parameters of the interaction can be extracted from the fit and are compared with recent theoretical values.

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Photoassociation of Ultracold Atoms: A New Spectroscopic Technique

Cited by 246 publications

References 174 publications

Intensity Dependence of Photoassociation in a Quantum Degenerate Atomic Gas

Intensity Dependence of Photoassociation in a Quantum Degenerate Atomic Gas

On the long-range and short-range behavior of potentials from reproducing kernel Hilbert space interpolation

Microwave electronic spectrum of the Ne⋯Ne+ long-range complex: The interaction potential

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