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arXiv · 2509.07736

Continuous cloud position spectroscopy using a magneto-optical trap

Benedikt Heizenreder·Ananya Sitaram·Sana Boughdachi·Andrew von Hörsten·Yan Xie·Andreas Brodschelm·Florian Schreck
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Abstract

We demonstrate a continuous spectroscopy technique with frequency sensitivity well below the natural transition linewidth, while maintaining a locking range hundreds of times larger. The method exploits the position dependence of a continuous, broadband magneto-optical trap operating on the 7.5 kHz-wide intercombination line of strontium. We show that the frequency sensitivity is fundamentally insensitive to the effective MOT laser linewidth. By applying active feedback on the MOT position to a dispersion-optimized frequency comb, which serves as the reference for stabilizing the MOT laser [1], we achieve a frequency instability below $4.4\times10^{-13}$ after 400 s of averaging in both the optical and radio-frequency domains, surpassing the performance of conventional hot-vapor modulation transfer spectroscopy. Our method is a broadly applicable alternative route to frequency references in the high $10^{-14}$ range around 100 s.

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Benedikt Heizenreder, Ananya Sitaram, Sana Boughdachi, Andrew von Hörsten, Yan Xie, Andreas Brodschelm, Florian Schreck. 2026-02-19. Continuous cloud position spectroscopy using a magneto-optical trap. https://doi.org/10.1103/wdp6-98wh

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