Simultaneous sub-Doppler laser cooling and optical trapping of bosonic 39K-133Cs and 41K-133Cs mixtures
Abstract
We report simultaneous sub-Doppler cooling and optical dipole trapping of 39K-Cs and 41K-Cs mixtures. Both mixtures are cooled to temperatures ∼10 μK, achieving performance comparable to that obtained with each species individually. To the best of our knowledge, this constitutes the first realization of a laser-cooled and optically trapped 41K-Cs mixture. For the 39K-Cs mixture, we additionally implement parallel spin-resolved Feshbach spectroscopy enabled by Stern-Gerlach separation. For potassium isotopes, we implement sub-Doppler cooling with D1-line gray molasses, while for cesium the entire cooling sequence is implemented using D2 transitions. We spin-polarize the atoms and confine Bose-Bose mixtures in a 1064 nm optical dipole trap. Using the resulting 39K-Cs samples, we observe 14 heteronuclear Feshbach loss features. Five agree with resonances reported previously, while nine have, to the best of our knowledge, not been observed experimentally before, including p-wave features and resonances in additional spin channels. The shorter lifetime of the 41K-Cs mixture in the optical dipole trap currently hinders systematic Feshbach spectroscopy, which we therefore do not pursue in this work. To characterize this limitation quantitatively, we study the decay dynamics of 39K-Cs and 41K-Cs mixtures under comparable temperature and density conditions, revealing a substantially stronger nonexponential loss in the 41K-Cs mixture. The demonstrated preparation of ultracold 41K-Cs mixtures provides a starting point for Feshbach-resonance and photoassociation spectroscopy of this previously unexplored isotopologue. Such measurements are essential for identifying suitable pathways for magnetoassociation and coherent optical transfer, and ultimately for the production of ultracold ground-state 41KCs molecules.
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BibTeX
@misc{bochenski2026simultaneous,
title = {{Simultaneous sub-Doppler laser cooling and optical trapping of bosonic $^39$K-$^133$Cs and $^41$K-$^133$Cs mixtures}},
author = {Mateusz Bocheński and Jakub Dobosz and Koray Dinçer and Paweł Arciszewski and Mariusz Semczuk},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.09003},
eprint = {2609.09003},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.09003},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Simultaneous sub-Doppler laser cooling and optical trapping of bosonic ^39K-^133Cs and ^41K-^133Cs mixtures
AU - Mateusz Bocheński
AU - Jakub Dobosz
AU - Koray Dinçer
AU - Paweł Arciszewski
AU - Mariusz Semczuk
PY - 2026
DA - 2026/09/08
PB - arXiv
DO - 10.48550/arxiv.2609.09003
UR - https://arxiv.org/abs/2609.09003
AB - We report simultaneous sub-Doppler cooling and optical dipole trapping of ^39K-Cs and ^41K-Cs mixtures. Both mixtures are cooled to temperatures ∼10 μK, achieving performance comparable to that obtained with each species individually. To the best of our knowledge, this constitutes the first realization of a laser-cooled and optically trapped ^41K-Cs mixture. For the ^39K-Cs mixture, we additionally implement parallel spin-resolved Feshbach spectroscopy enabled by Stern-Gerlach separation. For potassium isotopes, we implement sub-Doppler cooling with D_1-line gray molasses, while for cesium the entire cooling sequence is implemented using D_2 transitions. We spin-polarize the atoms and confine Bose-Bose mixtures in a 1064 nm optical dipole trap. Using the resulting ^39K-Cs samples, we observe 14 heteronuclear Feshbach loss features. Five agree with resonances reported previously, while nine have, to the best of our knowledge, not been observed experimentally before, including p-wave features and resonances in additional spin channels. The shorter lifetime of the ^41K-Cs mixture in the optical dipole trap currently hinders systematic Feshbach spectroscopy, which we therefore do not pursue in this work. To characterize this limitation quantitatively, we study the decay dynamics of ^39K-Cs and ^41K-Cs mixtures under comparable temperature and density conditions, revealing a substantially stronger nonexponential loss in the ^41K-Cs mixture. The demonstrated preparation of ultracold ^41K-Cs mixtures provides a starting point for Feshbach-resonance and photoassociation spectroscopy of this previously unexplored isotopologue. Such measurements are essential for identifying suitable pathways for magnetoassociation and coherent optical transfer, and ultimately for the production of ultracold ground-state ^41KCs molecules.
ER -