Towards a spin-squeezing-enhanced atom interferometer in an optical cavity.

Atom interferometers are state-of-the-art devices that exploit the wave-like nature of matter to measure various physical observables, including (but not limited to) acceleration forces, time, and magnetic fields [1]. The phase resolution of classical interferometers is limited by the standard quantum limit. Many atom interferometer schemes that entangle the internal spin states have demonstrated successful metrological enhancement up to 18.5 dB, and direct phase measurement enhancement (in a Ramsey sequence) up to 11.8 dB [2, 3]. However, there is room for improvement for atom interferometers which map the entangled atomic states onto momentum space (spatially separated arms). Most recently, a group in Hannover demonstrated an atom interferometric gravimeter with 1.7 dB entanglement enhancement [4].

We report the progress of our experiment: a spin-squeezed Mach-Zehnder atom interferometer enabled by atom-light interactions. A high-finesse traveling-wave cavity mediates both the far-off-resonant dipole trap and counter-propagating Raman tones. Initial atom-atom correlations are generated through one-axis twisting and quantum non-demolition protocols. State-dependent Raman kicks transfer momentum, mapping internal degrees of freedom and correlations to momentum space. Specifically, we present updates on cavity characteristics, atomic state preparation via optical pumping, squeezing protocols, and AC Stark shift compensation.

[1] Stuart S Szigeti, Onur Hosten, and Simon A Haine. Applied Physics Letters, 118(14), 2021.

[2] Onur Hosten, Nils J Engelsen, Rajiv Krishnakumar, and Mark A Kasevich. Nature, 529(7587):505–508, 2016.

[3] Simone Colombo, Edwin Pedrozo-Penafiel, Albert F Adiyatullin, Zeyang Li, Enrique Mendez, Chi Shu, and Vladan Vuletic. Nature Physics, 18(8):925–930, 2022.

[4] Christophe Cassens, Bernd Meyer-Hoppe, Ernst Rasel, and Carsten Klempt. arXiv preprint arXiv:2404.18668, 2024.