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Lambda-enhanced gray molasses in a tetrahedral laser beam geometry



Daniel Barker, Eric Norrgard, Nikolai Klimov, James A. Fedchak, Julia Scherschligt, Stephen Eckel


We report observation of sub-Doppler cooling of lithium using an irregular-tetrahedral laser beam arrangement, which is produced by a nanofabricated diffraction grating. We are able to capture 11(2) % of the lithium atoms from a grating magneto-optical trap into Lambda-enhanced D1 gray molasses. The molasses cools the captured atoms to a radial temperature of 60(9) uK and an axial temperature of 23(3) uK. In contrast to results from conventional counterpropagating beam configurations, we do not observe cooling when our optical fields are detuned from Raman resonance. An optical Bloch equation simulation of the cooling dynamics agrees with our data. Our results show that grating magneto-optical traps can serve as a robust source of cold atoms for tweezer-array and atom-chip experiments, even when the atomic species is not amenable to sub-Doppler cooling in bright optical molasses.
Optics Express


laser cooling, optical molasses, optical Bloch equations, cold core technology, cold atom vacuum standard


Barker, D. , Norrgard, E. , Klimov, N. , Fedchak, J. , Scherschligt, J. and Eckel, S. (2022), Lambda-enhanced gray molasses in a tetrahedral laser beam geometry, Optics Express, [online],, (Accessed June 20, 2024)


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Created March 14, 2022, Updated November 29, 2022