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arXiv:2306.02698

Dual-species Bose-Einstein condensates of $^{7}$Li and $^{133}$Cs

Y.-D. Chen, W. -X. Li, Y.-T. Sun, Q. -C. Chen, P. -Y. Chang, Shih-Kuang Tung

Published Jun 5, 2023• 0 citations
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Abstract

We report the creation of dual-species Bose-Einstein condensates (BECs) of $^{7}$Li and $^{133}$Cs. These BECs are formed in a bichromatic optical dipole trap created with 1550-nm and 780-nm laser beams. During the production process, an external magnetic field of 886~G is applied to adjust the scattering lengths to $a_{\rm{Cs}} = 123a_0$, $a_{\rm{Li}} = 484a_0$, and $a_{\rm{LiCs}} = 248a_0$. These scattering lengths allow for efficient evaporation and sympathetic cooling. The dual-species BECs are typically produced with $1.5\times 10^4$ Cs atoms and $6.0\times 10^3$ Li atoms. This quantum degenerate mixture of Li and Cs provides an ideal platform for exploring phenomena such as polarons and Efimov trimers, as well as for creating ground-state LiCs molecules.

DOI
10.48550/arxiv.2306.02698

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Dual-species Bose-Einstein condensates of 7^{7}7Li and 133^{133}133Cs
We report the creation of dual-species Bose-Einstein condensates (BECs) of 7^{7}7Li and 133^{133}133Cs. These BECs are formed in a bichromatic optical dipole trap created with 1550-nm and 780-nm laser beams. During the production process, an external magnetic field of 886~G is applied to adjust the scattering lengths to aCs=123a0a_{\rm{Cs}} = 123a_0aCs​=123a0​, aLi=484a0a_{\rm{Li}} = 484a_0aLi​=484a0​, and aLiCs=248a0a_{\rm{LiCs}} = 248a_0aLiCs​=248a0​. These scattering lengths allow for efficient evaporation and sympathetic cooling. The dual-species BECs are typically produced with 1.5×1041.5\times 10^41.5×104 Cs atoms and 6.0×1036.0\times 10^36.0×103 Li atoms. This quantum degenerate mixture of Li and Cs provides an ideal platform for exploring phenomena such as polarons and Efimov trimers, as well as for creating ground-state LiCs molecules.
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We report the production of 39K and 87Rb Bose–Einstein condensates (BECs) in the lowest hyperfine states | F = 1,mF = 1 〉 simultaneously. We collect atoms in bright/dark magneto-optical traps (MOTs) of 39K/87Rb to overcome the light-assisted losses of 39K atoms. Gray molasses cooling on the D1 line of the 39K is used to effectively increase the phase density, which improves the loading efficiency of 39K into the quadrupole magnetic trap. Simultaneously, the normal molasses is employed for 87Rb. After the microwave evaporation cooling on 87Rb in the optically plugged magnetic trap, the atoms mixture is transferred to a crossed optical dipole trap, where the collisional properties of the two species in different combinations of the hyperfine states are studied. The dual species BECs of 39K and 87Rb are obtained by further evaporative cooling in an optical dipole trap at a magnetic field of 372.6 G with the background repulsive interspecies scattering length a KRb = 34 a 0 (a 0 is the Bohr radius) and the intraspecies scattering length a K = 20.05a 0.
We report the production of quantum degenerate Bose-Bose mixtures of Cs and Yb with both attractive (Cs + 174Yb) and repulsive (Cs + 170Yb) interspecies interactions. Dual-species evaporation is performed in a bichromatic optical dipole trap that combines light at 1070 nm and 532 nm to enable control of the relative trap depths for Cs and Yb. Maintaining a trap which is shallower for Yb throughout the evaporation leads to highly efficient sympathetic cooling of Cs for both isotopic combinations at magnetic fields close to the Efimov minimum in the Cs three-body recombination rate at around 22 G. For Cs + 174Yb, we produce quantum mixtures with typical atom numbers of NYb ∼ 5 × 104 and NCs ∼ 5 × 103. We find that the attractive interspecies interaction (characterized by the scattering length aCsYb = −75a0) is stabilized by the repulsive intraspecies interactions. For Cs + 170Yb, we produce quantum mixtures with typical atom numbers of NYb ∼ 4 × 104 and NCs ∼ 1 × 104. Here, the repulsive interspecies interaction (aCsYb = 96a0) can overwhelm the intraspecies interactions, such that the mixture sits in a region of partial miscibility
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