In their paper "Entanglement-enhanced matter-wave interferometry in a high-finesse cavity" Nature (2022), Greve et. al. claim to use entanglement in a matter-wave interferometer to achieve a sensitivity beyond that achievable with the same number of independent particles -- a limit known as the standard quantum limit (SQL). In particular, using squeezed momentum states of 700 atoms, the authors claim to directly observe a sensitivity 3.4 dB (a factor of 1.5) below the SQL. This claim is incorrect. The authors do not measure anything beyond the SQL, nor do they achieve a sensitivity beyond what one could obtain with a single atom. The achieved sensitivity is at least a factor of 39 worse than the claimed value.
@article{arxiv.2301.04396,
title = {Matters Arising: Entanglement-enhanced matter-wave interferometry in a high-finesse cavity},
author = {Liam P. McGuinness},
journal= {arXiv preprint arXiv:2301.04396},
year = {2023}
}
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Matters arising comment on: https://doi.org/10.1038/s41586-022-05197-9