Mainz 2026 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 5: Laser Cooling and Trapping
Q 5.4: Talk
Monday, March 2, 2026, 12:30–12:45, P 11
Λ-enhanced gray-molasses loading and EIT cooling of neutral atoms in nanophotonic traps — Lukas Pache, Antoine Glicenstein, Arno Rauschenbeutel, •Philipp Schneeweiss, Jürgen Volz, and Riccardo Pennetta — Department of Physics, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
Nanophotonic waveguides enable the observation of strong interactions between guided photons and ensembles of laser-cooled atoms. However, nanophotonic traps for cold atoms typically have mode volumes ≪λ3, far smaller than for free-space optical tweezers. This makes efficient loading of these traps challenging, thereby limiting the total number of waveguide-coupled atoms. Here, we implement Λ-enhanced gray-molasses (GM) in a nanofiber-based cold-atom setup and observe a 7-fold increase in the trap loading efficiency. We operate in an unconventional regime for GM cooling, given that our optical traps have a depth of only 22 µK. Despite this, we load more than 2000 atoms, achieving optical depths exceeding 100. After loading, using the GM beams, we perform efficient EIT-assisted cooling that is found to increase the trap storage time to 400(9) ms. This is a 5-fold improvement over the passive storage time. Remarkably, EIT-cooling also works with a single nanofiber-guided beam, requiring only about 100 pW of optical power. Our results provide an effective method to boost both the loading rate and the storage time of nanophotonic atom traps. Since GM employs blue-detuned light, they also offer a pathway to surpass the collisional blockade in nanophotonic traps and explore collective radiative phenomena such as selective radiance.
Keywords: laser cooling; cold atoms; optical trap; EIT; gray molasses