QuantumFrontiers Success Stories: Tests of fundamental physics – QuantumFrontiers

Measurements eighty times more accurate

The upper bound on a drift of the fine-structure constant, α, has been improved by almost two orders of magnitude (×80) compared to the state of the art at the start of QuantumFrontiers in 2019. This current record at a level of 1.8(2.5) ×10^–19/yr has been achieved through frequency comparisons between sensitive optical clocks [2]. These measurements simultaneously improve the constraint on a possible violation of local position invariance (LPI), and the bound on non-gravitational couplings between ultralight dark matter candidates and normal matter by more than an order of magnitude [2, 3], as well as topological dark matter [4]. These results are complemented by orders of magnitude tighter bounds on light DM-to-matter coupling established by the gravitational wave detector GEO600 [5]. We have put the most stringent spectroscopic bounds on a possible 5th force, coupling electrons and neutrons, using isotope shift spectroscopy of Ca¹⁴⁺/Ca⁺ and Yb/Yb⁺ [6].

And the best tests of the Universality of Free Fall

Concerning gravity, scientists of QuantumFrontiers have established the best quantum and classical tests of the Universality of Free Fall (UFF) using dual species atom interferometry [7] and classical particles as part of the MICROSCOPE collaboration [8], as well as improved the bound on Local Lorentz Invariance (LLI) in the electron-photon sector by more than two orders of magnitude through comparisons of different orientations of electron orbitals [9, 10].

We have developed interferometer configurations to test the universality of the gravitational redshift and free fall using atom interferometry with clock states [11], which will be implemented in the VLBAI facility. Moreover, QuantumFrontiers has introduced conceptual innovations for testing alternative theories of relativity and assessing gravitational fields of quantum objects (e.g. nanoparticles) [12–14], establishing a robust foundation for further exploration of gravitational phenomena.

This article is part of a series on QuantumFrontiers success stories

Topical Groups involved

Optical Clocks in Networks

Publications

Bibliography

[1] V. V. Singh, J. Müller, et int, C. Lämmerzahl. Equivalence of Active and Passive Gravitational Mass Tested with Lunar Laser Ranging.
Phys. Rev. Lett. 131. doi:10.1103/physrevlett.131.021401 (2023).

[2] M. Filzinger, S. Dörscher, et int, N. Huntemann. Improved Limits on the Coupling of Ultralight Bosonic Dark Matter to Photons from Optical Atomic Clock Comparisons.
Physical Review Letters 130. doi:10. 1103/physrevlett.130.253001 (2023).

[3] A. Banerjee, D. Budker, et int, M. Safronova. Oscillating nuclear charge radii as sensors for ultralight dark matter.
arXiv: 2301.10784 [hep-ph] (2023).

[4] B. M. Roberts, P. Delva, et int, P. Wolf. Search for transient variations of the fine structure constant and dark matter using fiber-linked optical atomic clocks.
New Journal of Physics 22, 093010. doi:10.1088/1367- 2630/abaace (2020).

[5] S. M. Vermeulen, P. Relton, et int, H. Wittel. Direct limits for scalar field dark matter from a gravitational-wave detector.
Nature 600, 424–428. doi:10.1038/s41586-021-04031-y (2021). page 82 of 120 4 Research Programme

[6] M. Door, C.-H. Yeh, et int, T. E. Mehlstäubler. Search for new bosons with ytterbium isotope shifts.
arXiv: 2403.07792 [physics.atom-ph] (2024).

[7] H. Albers, A. Herbst, et int, D. Schlippert. Quantum test of the Universality of Free Fall using rubidium and potassium.
The European Physical Journal D 74. doi:10.1140/epjd/e2020-10132-6 (2020).

[8] P. Touboul, G. Métris, et int, P. Visser. MICROSCOPE Mission: Final Results of the Test of the Equivalence Principle.
Physical Review Letters 129. doi:10.1103/physrevlett.129.121102 (2022).

[9] C. Sanner, N. Huntemann, et int, S. G. Porsev. Optical clock comparison for Lorentz symmetry testing.
Nature 567, 204–208. doi:10.1038/s41586-019-0972-2 (2019)

[10] L. S. Dreissen, C.-H. Yeh, et int, T. E. Mehlstäubler. Improved bounds on Lorentz violation from composite pulse Ramsey spectroscopy in a trapped ion.
Nature Commun. 13. doi:10.1038/s41467-022-34818-0 (2022).

[11] C. Ufrecht, F. Di Pumpo, et int, E. Giese. Atom-interferometric test of the universality of gravitational redshift and free fall.
Physical Review Research 2. doi:10.1103/physrevresearch.2.043240 (2020).

[12] P. H. Morais, I. P. Lobo, et int, V. B. Bezerra. Modified particle lifetimes as a signature of deformed relativity.
Physics Letters B 848, 138380. doi:10.1016/j.physletb.2023.138380 (2024).

[13] F. Spengler, D. Rätzel, D. Braun. Perspectives of measuring gravitational effects of laser light and particle beams.
New Journal of Physics 24, 053021. doi:10.1088/1367-2630/ac5372 (2022).

[14] R. Barzel, M. Gündoğan, et int, C. Lämmerzahl. Entanglement dynamics of photon pairs and quantum memories in the gravitational field of the earth.
Quantum 8, 1273. doi:10.22331/q-2024-02-29-1273 (2024).

Success Story: Tests of fundamental physics

Measurements eighty times more accurate

And the best tests of the Universality of Free Fall

This article is part of a series on QuantumFrontiers success stories

Topical Groups involved

Publications