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Prospects for detecting new dark physics with the next generation of atomic clocks

Benjamin Elder1,*, Giorgio Mentasti1,†, Elizabeth Pasatembou1,‡, Charles F. A. Baynham1, Oliver Buchmueller1,2, Carlo R. Contaldi1, Claudia de Rham1, Richard Hobson1, and Andrew J. Tolley1

  • *Contact author: b.elder@imperial.ac.uk
  • †Contact author: g.mentasti21@imperial.ac.uk
  • ‡Contact author: e.pasatembou21@imperial.ac.uk
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Phys. Rev. D 112, 044053 – Published 26 August, 2025

DOI: https://doi.org/10.1103/vghm-4s5p

Abstract

Wide classes of new fundamental physics theories cause apparent variations in particle mass ratios in space and time. In theories that violate the weak equivalence principle (EP), those variations are not uniform across all particles and may be detected with atomic and molecular clock frequency comparisons. In this work we explore the potential to detect those variations with near-future clock comparisons. We begin by searching published clock data for variations in the electron-proton mass ratio. We then undertake a statistical analysis to model the noise in a variety of clock pairs that can be built in the near future according to the current state of the art, determining their sensitivity to various fundamental physics signals. Those signals are then connected to constraints on fundamental physics theories that lead directly or indirectly to an effective EP-violating, including those motivated by dark matter, dark energy, the vacuum energy problem, unification or other open questions of fundamental physics. This work results in projections for tight new bounds on fundamental physics that could be achieved with atomic and molecular clocks within the next few years. Our code for this work is packaged into a forecast tool that translates clock characteristics into bounds on fundamental physics.

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Phys. Rev. D 112, 044053– Published 26 August, 2025
  • Received 23 April 2025
  • Accepted 18 July 2025
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