Collisions between Ultracold Molecules and Atoms in a Magnetic Trap

Jurgilas, S.; Chakraborty, A.; Rich, C. J. H.; Caldwell, L.; Williams, H. J.; Fitch, N. J.; Sauer, B. E.; Frye, Matthew D.; Hutson, Jeremy M.; Tarbutt, M. R.

Abstract

We prepare mixtures of ultracold CaF molecules and Rb atoms in a magnetic trap and study their inelastic collisions. When the atoms are prepared in the spin-stretched state and the molecules in the spin-stretched component of the first rotationally excited state, they collide inelastically with a rate coefficient k 2 = ( 6.6 ± 1.5 ) × 10 − 11     cm 3 / s at temperatures near 100     μ K . We attribute this to rotation-changing collisions. When the molecules are in the ground rotational state we see no inelastic loss and set an upper bound on the spin-relaxation rate coefficient of k 2 < 5.8 × 10 − 12     cm 3 / s with 95% confidence. We compare these measurements to the results of a single-channel loss model based on quantum defect theory. The comparison suggests a short-range loss parameter close to unity for rotationally excited molecules, but below 0.04 for molecules in the rotational ground state.

Citation

Jurgilas, S., Chakraborty, A., Rich, C., Caldwell, L., Williams, H., Fitch, N., …Tarbutt, M. (2021). Collisions between Ultracold Molecules and Atoms in a Magnetic Trap. Physical Review Letters, 126(15), Article 153401. https://doi.org/10.1103/physrevlett.126.153401

• Journal Article Type: Article
• Acceptance Date: Mar 4, 2021
• Online Publication Date: Apr 13, 2021
• Publication Date: Apr 16, 2021
• Deposit Date: May 6, 2021
• Publicly Available Date: Sep 30, 2021
• Journal: Physical Review Letters
• Print ISSN: 0031-9007
• Electronic ISSN: 1079-7114
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 126
• Issue: 15
• Article Number: 153401
• DOI: https://doi.org/10.1103/physrevlett.126.153401