Large momentum transfer atom interferometry on the clock transition of 87Sr

Invited Talk

Long-baseline atom interferometers offer a promising approach for gravitational waves detection and dark matter searches, motivating large-scales initiatives such as AION [2], MAGIS [1] and AICE [4]. While most common atom interferometers use two-photon interactions, the sensitivity requirements of these applications benefit from a gradiometer configuration using a single-photon, narrow-line clock tran-sition. The long-lived excited state of an optical clock transition enables long interrogation time with negligible spontaneous emission losses, while the differential configuration on a single-photon transition allows for strong suppression of laser phase noise.

Large Momentum Transfer (LMT) techniques use additional light pulses to increase the momentum separation between the two interferometer arms, leading to an enhanced sensitivity. The realisation of LMT-enhanced atom interferometry on a single photon clock transition is therefore a crucial milestone towards long-baseline interferometers.

The AION project has recently built a gradiometer using the single-photon ¹S₀ - ³P₀ clock transition of ⁸⁷Sr, demonstrating laser phase noise rejection and operation at the standard quantum limit [3]. We have then implemented LMT-enhanced interferometry in a differential Mach-Zehnder configuration, reaching a momentum separation of 71 ¯hk between the interferometer arms. In this talk I will present the experimental steps we took for this demonstration.

References
[1] Mahiro Abe et al. “Matter-wave Atomic Gradiometer Interferometric Sensor (MAGIS-100)”. In: Quantum Sci. Technol. 6.4 (July 2021), p. 044003. doi: 10.1088/2058-9565/abf719.
[2] L. Badurina et al. “AION: An atom interferometer observatory and network”. In: Journal of Cos-mology and Astroparticle Physics 2020 (5 May 2020). issn: 14757516. doi: 10.1088/1475- 7516/
2020/05/011.
[3] C. F. A. Baynham et al. “A prototype differential atom interferometer for fundamental physics”. In: Nature 654.8119 (2026), pp. 622–628. issn: 1476-4687. doi: 10.1038/s41586-026-10617-1. url:
http://dx.doi.org/10.1038/s41586-026-10617-1.
[4] Charles Baynham et al. Letter of Intent: AICE - Atom Interferometry CERN Experiment. Letter of Intent submitted to CERN LHCC. 2025. arXiv: 2509.11867 [physics.atom-ph]. url: https:
//arxiv.org/abs/2509.11867.1

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