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Characteristics of a magneto-optical trap of molecules
摘要： We present the properties of a magneto-optical trap (MOT) of CaF molecules. We study the process of loading the MOT from a decelerated buffer-gas-cooled beam, and how best to slow this molecular beam in order to capture the most molecules. We determine how the number of molecules, the photon scattering rate, the oscillation frequency, damping constant, temperature, cloud size and lifetime depend on the key parameters of the MOT, especially the intensity and detuning of the main cooling laser. We compare our results to analytical and numerical models, to the properties of standard atomic MOTs, and to MOTs of SrF molecules. We load up to 2 × 10^4 molecules, and measure a maximum scattering rate of 2.5 × 10^6 s^?1 per molecule, a maximum oscillation frequency of 100 Hz, a maximum damping constant of 500 s^?1, and a minimum MOT rms radius of 1.5 mm. A minimum temperature of 730 μK is obtained by ramping down the laser intensity to low values. The lifetime, typically about 100 ms, is consistent with a leak out of the cooling cycle with a branching ratio of about 6 × 10^?6. The MOT has a capture velocity of about 11 m s^?1.
关键词： magneto-optical trap,ultracold molecules,laser-cooled molecules
更新于2025-09-23 15:21:01
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The RbSr <sup>2</sup> Σ <sup>+</sup> ground state investigated <i>via</i> spectroscopy of hot and ultracold molecules
摘要： We report on spectroscopic studies of hot and ultracold RbSr molecules, and combine the results in an analysis that allows us to fit a potential energy curve (PEC) for the X(1)2S+ ground state bridging the short-to-long-range domains. The ultracold RbSr molecules are created in a mK sample of Rb and Sr atoms and probed by two-colour photoassociation spectroscopy. The data yield the long-range dispersion coefficients C6 and C8, along with the total number of supported bound levels. The hot RbSr molecules are created in a 1000 K gas mixture of Rb and Sr in a heat-pipe oven and probed by thermoluminescence and laser-induced fluorescence spectroscopy. We compare the hot molecule data with spectra we simulated using previously published PECs determined by three different ab initio theoretical methods. We identify several band heads corresponding to radiative decay from the B(2)2S+ state to the deepest bound levels of X(1)2S+. We determine a mass-scaled high-precision model for X(1)2S+ by fitting all data using a single fit procedure. The corresponding PEC is consistent with all data, thus spanning short-to-long internuclear distances and bridging an energy gap of about 75% of the potential well depth, still uncharted by any experiment. We benchmark previous ab initio PECs against our results, and give the PEC fit parameters for both X(1)2S+ and B(2)2S+ states. As first outcomes of our analysis, we calculate the s-wave scattering properties for all stable isotopic combinations and corroborate the locations of Fano–Feshbach resonances between alkali Rb and closed-shell Sr atoms recently observed [V. Barbé et al., Nat. Phys., 2018, 14, 881]. These results and more generally our strategy should greatly contribute to the generation of ultracold alkali–alkaline-earth dimers, whose applications range from quantum simulation to state-controlled quantum chemistry.
关键词： spectroscopy,laser-induced fluorescence,thermoluminescence,ultracold molecules,photoassociation,potential energy curve,Fano-Feshbach resonances,RbSr molecules
更新于2025-09-19 17:15:36
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An approach to spin-resolved molecular gas microscopy
摘要： Ultracold polar molecules are an ideal platform for studying many-body physics with long-range dipolar interactions. Experiments in this field have progressed enormously, and several groups are pursuing advanced apparatus for manipulation of molecules with electric fields as well as single-atom-resolved in situ detection. Such detection has become ubiquitous for atoms in optical lattices and tweezer arrays, but has yet to be demonstrated for ultracold polar molecules. Here we present a proposal for the implementation of site-resolved microscopy for polar molecules, and specifically discuss a technique for spin-resolved molecular detection. We use numerical simulation of spin dynamics of lattice-confined polar molecules to show how such a scheme would be of utility in a spin-diffusion experiment.
关键词： quantum gas microscopy,quantum simulation,ultracold molecules,single-molecule control,dipolar spin models,optical lattices
更新于2025-09-09 09:28:46