Degenerate Raman sideband cooling of 39K

TL;DR

This paper demonstrates the first sub-Doppler laser cooling of 39K atoms using degenerate Raman sideband cooling on the D1 line, achieving high phase-space density and low temperatures suitable for advanced quantum experiments.

Contribution

First implementation of degenerate Raman sideband cooling on 39K atoms using the D1 transition, improving initial conditions for quantum applications.

Findings

Achieved 1.8 μK temperature in 39K atoms.

Produced spin-polarized samples with 1.4×10^8 atoms.

Attained phase-space densities ≥10^{-4}.

Abstract

We report on the first realization of sub-Doppler laser cooling of 39K atoms using degenerate 3D Raman sideband cooling. We take advantage of the well-resolved excited hyperfine states on the D1 optical transition to produce spin polarized samples with $1.4 \times 10^8$ atoms at temperatures of 1.8 $\mu$K. The phase-space densities are $\geq 10^{-4}$, which significantly improves the initial conditions for a subsequent evaporative cooling step. The presented cooling technique using the D1 line can be adapted to other atomic species and is applicable to high-resolution imaging schemes in far off-resonant optical lattices.