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arXiv:1608.07354 · Physical Review A

Production of large K41 Bose-Einstein condensates using D1 gray molasses

Hao-Ze Chen, Xing-Can Yao, Yu-Ping Wu, Xiangpei Liu, Xiao-Qiong Wang, Yu‐Xuan Wang, Yu-Ao Chen, Jian-Wei Pan

Published Sep 8, 2016• 35 citations
arXivHTMLPDF

Abstract

We use ${D}_{1}$ gray molasses to achieve Bose-Einstein condensation of a large number of $^{41}\mathrm{K}$ atoms in an optical dipole trap. By combining a specific configuration of a compressed magneto-optical trap with ${D}_{1}$ gray molasses, we obtain a cold sample of $2.4\ifmmode\times\else\texttimes\fi{}{10}^{9}$ atoms with a temperature as low as 42 $\ensuremath{\mu}\mathrm{K}$. After magnetically transferring the atoms into the final glass cell, we perform a two-stage evaporative cooling. A condensate with up to $1.2\ifmmode\times\else\texttimes\fi{}{10}^{6}$ atoms in the lowest Zeeman state $|F=1,{m}_{F}=1\ensuremath{\rangle}$ is achieved in the optical dipole trap. Furthermore, we observe two narrow Feshbach resonances in the lowest hyperfine channel, which are in good agreement with theoretical predictions.

DOI
10.1103/physreva.94.033408

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We demonstrate the production of large 7Li^{7}\mathrm{Li}7Li Bose-Einstein condensates in an optical dipole trap using D1{D}_{1}D1​ gray molasses. The sub-Doppler cooling technique reduces the temperature of $4\ifmmode\times\else\texttimes\fi{}{10}^{9}$ atoms to $25\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\mathrm{K}$ in 3 ms. After microwave evaporation cooling in a magnetic quadrupole trap, we transfer the atoms to a crossed optical dipole trap, where we employ a magnetic Feshbach resonance on the $|F=1,{m}_{F}=1\ensuremath{\rangle}$ state. Fast evaporation cooling is achieved by tilting the optical potential using a magnetic field gradient on the top of the Feshbach field. Our setup produces pure condensates with $2.7\ifmmode\times\else\texttimes\fi{}{10}^{6}$ atoms in the optical potential for every 11 s. The trap tilt evaporation allows rapid thermal quench, and spontaneous vortices are observed in the condensates as a result of the Kibble-Zurek mechanism.
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