Ultracold Heteronuclear Mixture of Ground and Excited State Atoms

Abstract

We report on the realization of an ultracold mixture of lithium atoms in the ground state and ytterbium atoms in an excited metastable ( 3 P2) state. Such a mixture can support broad magnetic Feshbach resonances which may be utilized for the production of ultracold molecules with an electronic spin degree of freedom, as well as novel Efimov trimers. We investigate the interaction properties of the mixture in the presence of an external magnetic field and find an upper limit for the background interspecies two-body inelastic decay coefficient of K ′ 2 < 3 × 10 −12 cm 3 /s for the 3 P2 mJ = −1 substate. We calculate the dynamic polarizabilities of the Yb( 3 P2) magnetic substates for a range of wavelengths, and find good agreement with our measurements at 1064 nm. Our calculations also allow the identification of magic frequencies where Yb ground and metastable states are identically trapped and the determination of the interspecies van der Waals coefficients.Ultracold elemental mixtures provide unique opportunities to study few-and many-body physics with mass-mismatched atomic partners [1] and diatomic polar molecules [2, 3]. While the bulk of elemental mixture experiments have been performed using ground-state bialkali systems, the recent production of ground state mixtures of alkali and alkaline-earth-like atoms [4][5][6][7] further extend the experimental possibilities. These include powerful quantum simulation and information protocols [8] and tests of fundamental symmetries [9] with paramagnetic polar molecules. While tunable two-body interactions that are important for these advances have been proposed in such mixtures [10], they have not yet been experimentally detected.In this Letter we report the realization a new class of heteronuclear mixtures in which one atomic component is in an electronically excited state, using lithium ( 6 Li) and ytterbium ( 174 Yb) atoms. This establishes a highly mass-mismatched atomic mixture where tunable anisotropic interactions are expected to play a strong role [11], laying a foundation for future studies of ultracold trapped paramagnetic polar molecules and Efimov trimers with very large mass imbalance [12]. We measure inelastic interactions in the mixture and observe the relative suppression of interspecies inelastic processes. Our experimental methods also demonstrate new techniques of production and manipulation of spin components in the metastable 3 P 2 state of Yb.The study and control of anisotropic interactions is an increasingly important topic in ultracold atomic systems. In addition to their impact on many-body physics [3,8,13], anisotropic two-body interactions are proving to be of great interest for generating magnetically tunable interactions, as has been calculated theoretically [14] and observed experimentally in a mixture of ground and excited state Yb atoms [15]. The latter result applied in the context of the Li+Yb combination points to an alternative route towards tunable interactions, where the ground

A versatile dual-species Zeeman slower for caesium and ytterbium

“…A small number of groups, including ourselves, have constructed experiments with such studies in mind. [29][30][31][32] Owing to the novelty and exacting nature of such experiments, combined with the di culty of calculating ab initio the molecular properties, it is not yet clear which specific molecules will be most conducive to the above stated goals. However, the variety of diatomic molecules that are potentially realisable using laser-cooling methods will each o↵er unique properties for experimental study.…”

Efficient production of long-lived ultracold Sr2 molecules

“…This general technique can represent a valuable alternative for associating molecules containing non-magnetic atoms, and in particular for the creation of alkali -alkaline-earth dimers [44][45][46][47]. Such dimers have been attracting great attention as they can allow fascinating quantum simulations, thanks to their permanent magnetic and electric dipole moments [21].…”

Production and characterization of a dual species magneto-optical trap of cesium and ytterbium

“…[20][21][22] Whilst several groups have created ultracold ground-state bi-alkali dimers, [23][24][25][26][27] a few are now starting to study alkalialkaline earth systems. [28][29][30][31] The unpaired electron spin in such systems gives rise to a permanent magnetic dipole moment in addition to the ground state electric dipole moment, enabling extra control over the molecular interactions and allowing spin lattice models to be simulated. 20 The expanding list of species combinations being used has led to the development of novel cooling techniques, for example, Refs.…”

“…32 and 33, and to the design of apparatus for cooling and trapping more than one species. [23][24][25][26][27][28][29][30][31] In this paper, we describe the production and characterization of a dual species magneto-optical trap (MOT) of cesium (Cs) and ytterbium (Yb). We also outline the apparatus designed to study the interspecies scattering length.…”