Saturation in heteronuclear photoassociation of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow /><mml:mrow><mml:mn>6</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Li</mml:mi></mml:mrow><mml:mrow><mml:mn>7</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">Li</mml:mi></mml:math>

Schlöder, U.; Silber, C.; Deuschle, T.; Zimmermann, C.

doi:10.1103/physreva.66.061403

Cited by 44 publications

(38 citation statements)

References 27 publications

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“…For T 600 nK, K u p 2:5 10 ÿ8 cm 3 s ÿ1 , in good agreement with the full theoretical calculation and experiment. The saturation observed in previous experiments [22,23] is consistent with the unitarity limit, although at rates many orders of magnitude lower than observed here. It is interesting to speculate on how our results relate to the other proposed saturation mechanisms.…”

Section: P H Y S I C a L R E V I E W L E T T E R S Week Ending 22 Augsupporting

confidence: 71%

“…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 a quantum degenerate gas of 7 Li atoms as a function of laser intensity. The rate is observed to saturate at the highest intensities, where the corresponding rate constants are nearly 2 orders of magnitude larger than any previously measured.…”

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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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Section: P H Y S I C a L R E V I E W L E T T E R S Week Ending 22 Augsupporting

confidence: 71%

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Intensity Dependence of Photoassociation in a Quantum Degenerate Atomic Gas

et al. 2003

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“…As an alternative to Feshbach resonances, photoassociation is used to transform atomic pairs into molecules. Photoassociation has been extensively investigated for the homonuclear case [12], and there are already examples of successful heteronuclear photoassociation [13,14,15]. The advantage of photoassociation is the possibility to form molecules also in deeper lying bound states [16], where the internuclear distance is drastically reduced and the molecules behave more like composite particles with a well defined quantum statistics.…”

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Quantum-Degenerate Mixture of Fermionic Lithium and Bosonic Rubidium Gases

et al. 2005

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We report on the observation of sympathetic cooling of a cloud of fermionic 6 Li atoms which are thermally coupled to evaporatively cooled bosonic 87 Rb. Using this technique we obtain a mixture of quantum-degenerate gases, where the Rb cloud is colder than the critical temperature for BoseEinstein condensation and the Li cloud colder than the Fermi temperature. From measurements of the thermalization velocity we estimate the interspecies s-wave triplet scattering length |as| = 20 +9 −6 aB. We found that the presence of residual rubidium atoms in the |2, 1 and the |1, −1 Zeeman substates gives rise to important losses due to inelastic collisions.PACS numbers: 05.30. Fk, 05.30.Jp, 32.80.Pj, The recent realization of degenerate gases of homonuclear diatomic molecules is an important achievement for the physics of ultracold dilute quantum gases [1,2]. The key to this spectacular success was the use of Feshbach resonances which allow for an adiabatic transformation from free pairs to molecules in the least bound state close to the dissociation energy [3]. The large internal energy makes the gas unstable against collisions between the molecules, which transform the energy into kinetic energy of the collision partners [4]. The very long lifetimes of up to several 10 s observed for dimers made of fermionic 6 Li [2] are explained by the fact that the atoms are only loosely bound with a binding energy of 1 µK such that they still behave very much like individual atoms [5]. Collisions are thus suppressed due to Pauli-blocking. Fermionic lithium is now a very promising candidate for exploring the cross-over regime between the Bardeen-Cooper-Schrieffer (BCS) model for superconductivity based on Cooper pairs and the regime of a Bose-Einstein condensate of composite bosons [6].In contrast to homonuclear dimers molecules made of two different atomic species exhibit a permanent electric dipole moment. The LiRb dimer has a very large permanent electric dipole moment of up to 4.2 Debye [7]. The intermolecular interaction in such a heteronuclear gas has a pronounced long-range character, which fundamentally alters its behavior at low temperatures [8] and brings global properties of the gas into play. The geometric shape of the cloud for instance will influence the total interaction energy and thus the stability of the gas [9].A possible approach to generate a polar molecular gas would use a Feshbach resonance in close analogy to the homonuclear experiments [1,2]. Only recently first heteronuclear Feshbach resonances have been observed [10]. Weakly bound heteronuclear molecules are expected to be relatively stable against collisions if one of the two atoms is a fermion [5]. For such molecules Pauli-blocking is at least partially effective, even though reactive collisions may reduce their lifetime [11]. As an alternative to Feshbach resonances, photoassociation is used to transform atomic pairs into molecules. Photoassociation has been extensively investigated for the homonuclear case [12], and there are already examples of successf...

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“…In fact, fulfillment of exactly such conditions have enabled experimental demonstrations of Rabi oscillations in PA [18,19]. Saturation effects in PA have also been studied experimentally by many groups [56][57][58].…”

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confidence: 99%

Photoassociative cooling and trapping of a pair of interacting atoms

2016

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We show that it is possible to cool interacting pairs of atoms by a lin ⊥ lin Sisyphus-like laser cooling scheme using counter-propagating photoassociation (PA) lasers. It is shown that the center-of-mass motion (c.m.) of atom pairs can be trapped in molecular spin-dependent periodic potentials generated by the lasers.The proposed scheme is most effective for narrow-line PA transitions. We illustrate this with numerical calculations using fermionic 171 Yb atoms as an example.

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Saturation in heteronuclear photoassociation of6Li7Li

Cited by 44 publications

References 27 publications

Intensity Dependence of Photoassociation in a Quantum Degenerate Atomic Gas

Intensity Dependence of Photoassociation in a Quantum Degenerate Atomic Gas

Quantum-Degenerate Mixture of Fermionic Lithium and Bosonic Rubidium Gases

Photoassociative cooling and trapping of a pair of interacting atoms

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