A prototype differential atom interferometer for fundamental physics
- C. F. A. Baynham
- R. Hobson
- O. Buchmüller
- D. Evans
- L. Hawkins
- L. Iannizzotto Venezze
- A. Josset
- D. Lee
- E. Pasatembou
- B. E. Sauer
- M. R. Tarbutt
- T. Walker
- O. Ennis
- U. Chauhan
- A. Brzakalik
- S. Dey
- S. Hedges
- B. Stray
- M. Langlois
- K. Bongs
- T. Hird
- S. Lellouch
- M. Holynski
- B. Bostwick
- J. Chen
- Z. Eyler
- V. Gibson
- T. L. Harte
- C. C. Hsu
- M. Karzazi
- C. Lu
- B. Millward
- J. Mitchell
- N. Mouelle
- B. Panchumarthi
- J. Scheper
- U. Schneider
- X. Su
- Y. Tang
- K. Tkalčec
- M. Zeuner
- S. Zhang
- Y. Zhi
- L. Badurina
- A. Beniwal
- D. Blas
- J. Carlton
- J. Ellis
- C. McCabe
- G. Parish
2026-06-17
Gravitational waves and ultralight dark matter are among the most compelling frontiers in fundamental physics, motivating proposals for very-long-baseline atom interferometerssuch as AION 1 , MAGIS 2 , AICE 3 and AEDGE 4 that aim to detect at frequencies at which ground-based 5 and space-borne 6 laser interferometers lose sensitivity. Very-long-baseline atom interferometers look for signals by comparing the quantum phase evolution of widely separated atomic ensembles interrogated by a common laser. However, their performance depends critically on suppressing noise sources, particularly laser phase noise. The experimental validation of such noise rejection remains an important challenge. Here we demonstrate a prototype differential atom interferometer based on the single-photon clock transition of fermionic 87 Sr. Thus, we obtain a gradiometer configuration with a species intrinsically suited to kilometre-scale and space-baseline operation. The instrument operates at the standard quantum limit 7 with no excess noise beyond atom shot noise. The differential configuration maintains quantum-limited sensitivity in the presence of several radians of artificially injected laser phase noise per shot, which emulates the conditions expected in a very-long-baseline atom interferometer. We also demonstrate the recovery of coherent oscillatory signals across a broad frequency range under fully phase-randomized conditions, a capability that is inaccessible to a single interferometer operating in the same regime. These results provide an experimental validation of the noise-immune measurement principle underlying very-long-baseline atom interferometers and mark an important step towards next-generation quantum sensors for gravitational-wave detection and searches for ultralight dark matter 8,9 .