An international team of scientists has pioneered a new method in the search for dark matter,utilizing the precision of optical atomic clocks to explore interactions beyond those previously considered. Researchers from the Physikalisch-Technische Bundesanstalt (PTB) and collaborating institutions are focusing on the potential coupling of dark matter to the fundamental building blocks of atomic nuclei-quarks and gluons-a novel approach published this week in Physical Review Letters. This work builds on existing efforts to detect dark matter via atomic clocks, previously focused on interactions with photons, and establishes new upper limits for these elusive interactions.
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11/25/2025 18:19
New Approach to the Search for Dark Matter
Optical atomic clocks are proving to be particularly effective tools in the hunt for dark matter. Previous research has focused on the potential interaction of dark matter with photons, but now an international team, including researchers from the Physikalisch-Technische Bundesanstalt (PTB), has identified a new avenue for investigation: exploring the coupling of dark matter to components within the atomic nucleus. An analysis of data from the PTB’s optical ytterbium single-ion clock has established new upper limits for the coupling of ultralight dark matter to quarks and gluons. The findings are published in the latest issue of the prestigious journal Physical Review Letters.
The search for dark matter remains one of the most significant challenges in modern physics. A particularly promising theoretical framework suggests that dark matter may be composed of extremely lightweight particles that behave as waves – so-called “ultralight” dark matter. This model predicts that previously undiscovered, weak interactions between dark matter and ordinary matter would cause minute oscillations in fundamental constants.
Because different atomic transitions respond with varying sensitivity to potential changes in these constants, comparisons between atomic clocks can be leveraged to search for ultralight dark matter. Optical atomic clocks, in particular, are known for their exceptional long-term stability and have already been successfully employed in this type of search. However, until now, these clocks have primarily been used to investigate coupling to light particles (photons).
Now, an international collaboration of scientists, including researchers from the PTB, has demonstrated that optical clocks can also be used to search for couplings between ultralight dark matter and the fundamental constituents of atomic nuclei – quarks and gluons. These interactions would induce oscillations in the nuclear charge radii, which in turn would affect the atomic transitions upon which optical clocks rely. An analysis of existing data from the PTB’s ytterbium single-ion clock yielded upper limits for the coupling of ultralight dark matter to quarks and gluons.
This work establishes a novel approach to utilizing optical clocks in the search for dark matter.
(es/ptb)
Contact for scientific information:
Dr. Nils Huntemann, PTB-Arbeitsgruppe 4.43 Optische Uhren mit gespeicherten Ionen, Telefon: (0531) 592-4430, nils.huntemann@ptb.de
Original publication:
A. Banerjee, D. Budker , M. Filzinger, N. Huntemann, G. Paz, G. Perez, S. Porsev, M. Safronova: Oscillating nuclear charge radii as sensors for ultralight dark matter. Phys. Rev. Lett. 135, 223001 (2025), DOI: https://doi.org/10.1103/37vw-gc1r
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The optical ytterbium single-ion clock of the PTB
Source: PTB
Copyright: PTB
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