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arXiv · 2505.10115

Collective light shifts of many longitudinal cavity modes induced by coupling to a cold-atom ensemble

Marin Ðujić·Mateo Kruljac·Lovre Kardum·Neven Šantić·Damir Aumiler·Ivor Krešić·Ticijana Ban
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Abstract

We experimentally study the interaction between a cold atom cloud and many longitudinal modes of a high quality Fabry-Perot cavity, by measuring signatures of collective light shifts in the cavity transmission spectrum of an optical frequency comb probe. Using a resonator coupled to more than $10^5$ intracavity atoms, we detect significant shifts of $\sim 100$ cavity modes simultaneously, which is a direct manifestation of physics beyond the hitherto explored regime of cavity-cold atom interaction with only single or few longitudinal modes at a time. For the cavity mode closest to the atomic resonance, we demonstrate a bistability in the transmission spectrum, arising due to a combined coupling of the cloud to an external pump laser and a cavity mode probed by the optical frequency comb. These results provide a first step toward deeper exploration of multifrequency cavity quantum electrodynamics, where ultrashort pulsed sources could be used for optical manipulation, cooling and entanglement of cold atoms in a resonator.

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Marin Ðujić, Mateo Kruljac, Lovre Kardum, Neven Šantić, Damir Aumiler, Ivor Krešić, Ticijana Ban. 2025-05-15. Collective light shifts of many longitudinal cavity modes induced by coupling to a cold-atom ensemble. https://doi.org/10.1103/fy4n-mj4d

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