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arXiv · 1811.02185

Sub-Doppler laser cooling of $^{39}$K via the 4S$\to$5P transition

Govind Unnikrishnan·Michael Gröbner·Hanns-Christoph Nägerl
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Abstract

We demonstrate sub-Doppler laser cooling of $ ^{39} $K using degenerate Raman sideband cooling via the 4S$_{1/2} \rightarrow $5P$ _{1/2} $ transition at 404.8 nm. By using an optical lattice in combination with a magnetic field and optical pumping beams, we obtain a spin-polarized sample of up to $5.6 \times 10^{7}$ atoms cooled down to a sub-Doppler temperature of 4 $\mu $K, reaching a peak density of $3.9 \times 10^{9}$ atoms/cm$ ^{3} $, a phase-space density greater than $ 10^{-5} $, and an average vibrational level of $ \langle \nu \rangle=0.6 $ in the lattice. This work opens up the possibility of implementing a single-site imaging scheme in a far-detuned optical lattice utilizing shorter wavelength transitions in alkali atoms, thus allowing improved spatial resolution.

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Govind Unnikrishnan, Michael Gröbner, Hanns-Christoph Nägerl. 2018-11-06. Sub-Doppler laser cooling of $^{39}$K via the 4S$\to$5P transition. https://doi.org/10.21468/scipostphys.6.4.047

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