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arXiv · 2002.00056

Sub-Doppler Cooling and Compressed Trapping of YO Molecules at $μ$K Temperatures

Shiqian Ding·Yewei Wu·Ian A. Finneran·Justin J. Burau·Jun Ye
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Abstract

Complex molecular structure demands customized solutions to laser cooling by extending its general set of principles and practices. Yttrium monoxide (YO) has unique intramolecular interactions. The Fermi-contact interaction dominates over the spin-rotation coupling, resulting in two manifolds of closely spaced states, with one of them possessing a negligible Landé g-factor. This unique energy level structure favors dual-frequency DC magneto-optical trapping (MOT) and gray molasses cooling (GMC). We report exceptionally robust cooling of YO at 4 $μ$K over a wide range of laser intensity, detunings (one and two-photon), and magnetic field. The magnetic insensitivity enables the spatial compression of the molecular cloud by alternating GMC and MOT under the continuous operation of the quadrupole magnetic field. A combination of these techniques produces a laser-cooled molecular sample with the highest phase space density in free space.

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Shiqian Ding, Yewei Wu, Ian A. Finneran, Justin J. Burau, Jun Ye. 2020-01-31. Sub-Doppler Cooling and Compressed Trapping of YO Molecules at $μ$K Temperatures. https://doi.org/10.1103/physrevx.10.021049

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