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Dispersive measurement of spin shot noise in a Bose-Einstein condensate

Kosuke Shibata1,2,*, Naota Sekiguchi3, Junnosuke Takai4, and Takuya Hirano1

  • *Contact author: shibata@qo.phys.gakushuin.ac.jp
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Phys. Rev. Research 7, 043040 – Published 14 October, 2025

DOI: https://doi.org/10.1103/md2j-t2qq

Abstract

We report dispersive spin shot noise measurement of a Bose-Einstein condensate (BEC). While dispersive probing has been used for quantum spin noise measurement of thermal and cold gases for decades, confirmative measurement of shot noise of real spin, i.e., the linear dependence of the spin variance on the number of atoms in a BEC, has been lacking. Here, we demonstrate precise spin noise measurement of a BEC of rubidium atoms at the spin shot noise level by polarization rotation using a two-color probe at optimal detunings, with power balance stabilization to suppress probe-induced excess spin noise. This work opens the possibility for the unexplored study of quantum spin fluctuations in multicomponent or spinor BECs and offers an approach to improve spin measurement precision, which is relevant to atomic spin-based sensors.

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Phys. Rev. Research 7, 043040– Published 14 October, 2025
  • Received 28 January 2025
  • Accepted 19 September 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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