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Atomic thermometry in optical lattice clocks: Model discrepancies and their impact on lattice light shifts

Irene Goti*, Tommaso Petrucciani, Stefano Condio, Filippo Levi, Davide Calonico, and Marco Pizzocaro†

  • *Contact author: i.goti@inrim.it
  • †Contact author: m.pizzocaro@inrim.it
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Phys. Rev. A 114, 053105 – Published 6 November, 2026

DOI: https://doi.org/10.1103/nzhn-34tp

Abstract

Accurate measurement of atomic temperature is fundamental for a wide range of applications, from quantum sensing to precision metrology. In optical lattice clocks, precise characterization of atomic temperature is required to minimize systematic uncertainties at the 10−18 level. In this work we investigate atomic temperature measurements in the ytterbium optical clock developed at INRIM, IT-Yb1, employing sideband and transverse Doppler spectroscopy across a wide range of trapping conditions in a one-dimensional optical lattice. By implementing clock-line-mediated Sisyphus cooling [Phys. Rev. Lett. 133, 053401 (2024)], we reduce the atomic temperature and enable operation at shallower lattice depths to D=50ER, where ER is the photon recoil energy. We compare temperature estimates obtained from the perturbed harmonic oscillator model with those derived using a Born-Oppenheimer model [Phys. Rev. A 101, 053416 (2020)]. Discrepancies of up to a factor of four are observed between the temperature estimates obtained with the two approximations. We assess the impact of these modeling differences on the evaluation of lattice light shifts and find relative frequency deviations of up to 8×10−17. Although sufficiently low atomic temperatures and the consistent use of theoretical models reduce these discrepancies to the low 10−18 level, these results motivate further investigations that will be relevant to state-of-the-art optical lattice clocks.

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Phys. Rev. A 114, 053105– Published 6 November, 2026
  • Received 10 July 2026
  • Accepted 19 October 2026
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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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