Clock atom interferometry makes use of narrow optical clock transitions to metastable excited states are the foundation for the world’s best atomic clocks. Such transitions naturally occur in fermions but are generally strongly forbidden in bosons. We compare and contrast several types of clock atom interferometers and explore their suitability for challenging applications with long- baseline sensors like gravitational wave detection and dark matter searches. We demonstrate a coherent three-photon excitation of a strongly forbidden clock transition in bosonic 88Sr and realize a proof-of-principle multiphoton clock atom interferometer. This method unlocks bosonic isotopes for next-generation quantum sensors like the long-baseline instrument MAGIS-100 [1].
[1] M. Abe, et al. (MAGIS Collaboration), Quantum Science and Technology 6 (2021)
