Resonant Coupling in the Formation of Ultracold Ground State Molecules via Photoassociation

Dion, Claude M.; Drag, Cyril; Dulieu, Olivier; Tolra, B. Laburthe; Masnou-Seeuws, F.; Pillet, P.

doi:10.1103/physrevlett.86.2253

Cited by 113 publications

(129 citation statements)

References 17 publications

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“…The excitation step from two atoms to the 0 + u or 1 g and 0 − g excited states is unlikely to be selective. The efficient stabilization mechanism for 0 + u has been identified as resonant spin-orbit coupling [31,41]. In a time-dependent process, resonant coupling leads to a dynamical enhancement of stabilization making the dump step even more efficient than deexcitation to Cs 2 lower triplet state molecules from 0 − g (P 3/2 ).…”

Section: Discussionmentioning

confidence: 99%

Short-pulse photoassociation in rubidium below theD1line

2006

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Photoassociation of two ultracold rubidium atoms and the subsequent formation of stable molecules in the singlet ground and lowest triplet states is investigated theoretically. The method employs laser pulses inducing transitions via excited states correlated to the 5S + 5P 1/2 asymptote. Weakly bound molecules in the singlet ground or lowest triplet state can be created by a single pulse while the formation of more deeply bound molecules requires a two-color pump-dump scenario. More deeply bound molecules in the singlet ground or lowest triplet state can be produced only if efficient mechanisms for both pump and dump steps exist. While long-range 1/R 3 -potentials allow for efficient photoassociation, stabilization is facilitated by the resonant spin-orbit coupling of the 0 + u states. Molecules in the singlet ground state bound by a few wavenumbers can thus be formed. This provides a promising first step toward ground state molecules which are ultracold in both translational and vibrational degrees of freedom.

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Section: Discussionmentioning

confidence: 99%

Short-pulse photoassociation in rubidium below theD1line

2006

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“…This is the simplest example of the formation of a chemical bond under ultracold conditions. The PA step is mostly controlled by long-range atom-atom interactions [28][29][30], while the SE step involves short-range interaction [24,31]. The knowledge of atom-atom interactions is thus required to fully describe the PA+SE process, which is possible in most cases.…”

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confidence: 99%

Theory of Long-Range Ultracold Atom-Molecule Photoassociation

2015

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The creation of ultracold molecules is currently limited to diatomic species. In this letter we present a theoretical description of the photoassociation of ultracold atoms and molecules to create ultracold excited triatomic molecules, thus being a novel example of light-assisted ultracold chemical reaction. The calculation of the photoassociation rate of ultracold Cs atoms with ultracold Cs2 molecules in their rovibrational ground state is reported, based on the solution of the quantum dynamics involving the atom-molecule long-range interactions, and assuming a model potential for the short-range physics. The rate for the formation of excited Cs3 molecules is predicted to be comparable with currently observed atom-atom photoassociation rates. We formulate an experimental proposal to observe this process relying on the available techniques of optical lattices and standard photoassociation spectroscopy.Ultracold dilute gases at temperatures much lower than 1 mK offer new opportunities for the study of elementary reactive processes between atoms and molecules. As emphasized in seminal review articles [1,2] this socalled ultracold chemistry is freed from averaging on large velocity distributions. Thus in this regime the quantum nature of the processes can be accessed, like the presence of resonances, or the sensitivity to long-range interactions which can induce anisotropic arrangements prior to the reaction. One of the most advanced experiments in this direction is undoubtedly under progress in JILA at Boulder, where quantum threshold collisions induced by tunneling through a centrifugal barrier between fermionic ultracold KRb molecules have been detected [3,4] [9] have been detected through atom trap losses. Three-body recombination in a Rb quantum gas has been characterized [10], and features associated to universal N -body (up to N = 5) resonances induced by collisions between atoms and weaklybound molecules have been observed in quantum degenerate gases [11][12][13][14][15][16].However the deep understanding of the collisional dynamics is still to come as none of these achievements were able to characterize the nature and the state distribution of the final products [17,18]. The heavy mass of alkalimetal species leads to a huge density of resonant states related to the numerous rovibrational levels accessible during an atom/molecule or a molecule/molecule collision, preventing them to be individually characterized. Models connecting the standard treatment of long-range interactions between particles to a statistical description of the resonances mostly resulting from short-range couplings have been developed [18][19][20][21]. The main quantitative uncertainty of such models arises from the estimation of the actual amount of resonant states which are indeed active during the collision.In this letter, we propose to use the well-known photoassociation (PA) process to get more insight into such collisions between ultracold atoms and molecules. PA of an ultracold atom pair is a laser-assisted collision creating an ...

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“…Another approach is to extend well-known techniques for producing ultracold (non-polar) homonuclear diatomic molecules in binary collisions of ultracold atoms, either through photoassociation [12,13,14,15,16], or Feshbach resonance [17,18]. In these methods, the translational and rotational temperatures of the molecules are limited only by the initial atomic sample, possibly providing access all the way to the quantum-degenerate regime [15,18].…”

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Production of Ultracold, PolarRbCs*Molecules via Photoassociation

et al. 2004

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We have produced ultracold, polar RbCs * molecules via photoassociation in a laser-cooled mixture of Rb and Cs atoms. Using a model of the RbCs * molecular interaction which reproduces the observed rovibrational structure, we infer decay rates in our experiments into deeply bound X 1 Σ + ground state RbCs vibrational levels as high as 5×10 5 s −1 per level. Population in such deeply bound levels could be efficiently transferred to the vibrational ground state using a single stimulated Raman transition, opening the possibility to create large samples of stable, ultracold polar molecules.PACS numbers: 32.80. Pj, 33.80.Ps, 34.50.Gb, 34.50.Rk Ultracold polar molecules, due to their strong, longrange, anisotropic dipole-dipole interactions, may provide access to qualitatively new regimes previously inaccessible to ultracold atomic and molecular systems. For example, they might be used as the qubits of a scalable quantum computer [1]. New types of highly-correlated many-body quantum states could become accessible such as BCS-like superfluids [2], supersolid and checkerboard states [3], or "electronic" liquid crystal phases [4]. Ultracold chemical reactions between polar molecules have been discussed [5], and might be controlled using electric fields [6]. Finally, the sensitivity of current moleculebased searches for violations of fundamental symmetries [7] might be increased to unprecedented levels.Cold, trapped polar molecules have so far only been produced using either buffer-gas cooling [8] or Starkslowing [9], at temperatures of ∼10-100 mK [8,9]. This is much higher than the ∼1-100 µK accessible with atoms, and attempts to bridge this gap with evaporative cooling may run afoul of predicted molecular Feshbach resonances [10] or inelastic losses [11].Another approach is to extend well-known techniques for producing ultracold (non-polar) homonuclear diatomic molecules in binary collisions of ultracold atoms, either through photoassociation [12,13,14,15,16], or Feshbach resonance [17,18]. In these methods, the translational and rotational temperatures of the molecules are limited only by the initial atomic sample, possibly providing access all the way to the quantum-degenerate regime [15,18]. An important limitation, however, is that the molecules are typically formed in weakly bound vibrational levels near dissociation, which may have vanishing electric dipole moments [19], and are unstable with respect to inelastic collisions [10,11,15]; therefore, a method for transferring them to the vibrational ground state is desirable [14].Several authors have discussed the extension of these methods to the formation of (heteronuclear) polar molecules in collisions between different atomic species [20,21,22,23]. In recent experiments NaCs + and RbCs + ions formed in the presence of near-resonant light have indeed been observed in small numbers [21]; however, these observations did not permit an analysis of their formation mechanism, nor demonstrate a method for producing neutral, ultracold polar molecules.In this Letter, we ...

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Resonant Coupling in the Formation of Ultracold Ground State Molecules via Photoassociation

Cited by 113 publications

References 17 publications

Short-pulse photoassociation in rubidium below theD1line

Short-pulse photoassociation in rubidium below theD1line

Theory of Long-Range Ultracold Atom-Molecule Photoassociation

Production of Ultracold, PolarRbCs*Molecules via Photoassociation

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