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Quasicontinuous sub-μK strontium source without a high-finesse cavity-stabilized laser

Sana Boughdachi1,2,*, Benedikt Heizenreder1,*, Ananya Sitaram1, Erik Dierikx3, Yan Xie3, Sander Klemann4, Paul Klop4, Jeroen Koelemeij5, Rafał Wilk2 et al.

Florian Schreck1,6 and Andreas Brodschelm2,†

  • *These authors contributed equally to this work.
  • †Contact author: NarrowLineComb@strontiumBEC.com
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Phys. Rev. Applied 25, 034053 – Published 16 March, 2026

DOI: https://doi.org/10.1103/3gnx-4s97

Abstract

We demonstrate a quasicontinuous sub-μK strontium source achieved without the use of a high-finesse cavity-locked laser. Our frequency reference is based on a dispersion-optimized, fiber-based frequency comb that enables sub-kHz linewidths. The long-term stability of the comb is defined by an external rf reference: either a 10 MHz rf signal from the Dutch Metrology Institute (VSL) or a tunable rf source whose long-term stability is maintained by monitoring and stabilizing the position of a narrow-line magneto-optical trap (MOT) [Sillus et al., Rev. Sci. Instrum., 92, 033204 (2021); Heizenreder et al., Continuous cloud position spectroscopy using a magneto-optical trap, Phys. Rev. Appl. (2026)]. The comb-stabilized system is benchmarked against a conventional cavity-locked laser and achieves comparable performance in broadband and single-frequency MOTs using the narrow 1S0→3P1 laser-cooling transition. We generate high-flux, sub-μK samples of all three bosonic strontium isotopes and demonstrate quasicontinuous outcoupling from the MOT. These results highlight the system’s suitability for compact, robust, and field-deployable continuous cold-atom devices.

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Phys. Rev. Applied 25, 034053– Published 16 March, 2026
  • Received 31 July 2025
  • Revised 15 January 2026
  • Accepted 6 February 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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