Abbasi, R.Ackermann, M.Adams, J.Agarwalla, S.K.Aguilar, J.A.Ahlers, M.Alameddine, J.M.Amin, N.M.Andeen, K.Anton, G.Argüelles, C.Ashida, Y.Athanasiadou, S.Ausborm, L.Axani, S.N.Bai, X.Balagopal V, A.Baricevic, M.Barwick, S.W.Basu, V.et al.2024-10-112024-10-112024Nature Physics, 2024; 20(6):913-9201745-24731745-2473https://hdl.handle.net/2440/142781Neutrino oscillations at the highest energies and longest baselines can be used to study the structure of spacetime and test the fundamental principles of quantum mechanics. If the metric of spacetime has a quantum mechanical description, its fuctuations at the Planck scale are expected to introduce non-unitary efects that are inconsistent with the standard unitary time evolution of quantum mechanics. Neutrinos interacting with such fuctuations would lose their quantum coherence, deviating from the expected oscillatory favour composition at long distances and high energies. Here we use atmospheric neutrinos detected by the IceCube South Pole Neutrino Observatory in the energy range of 0.5–10.0 TeV to search for coherence loss in neutrino propagation. We fnd no evidence of anomalous neutrino decoherence and determine limits on neutrino–quantum gravity interactions. The constraint on the efective decoherence strength parameter within an energy-independent decoherence model improves on previous limits by a factor of 30. For decoherence efects scaling as E2 , our limits are advanced by more than six orders of magnitude beyond past measurements compared with the state of the art.en© The Author(s), under exclusive licence to Springer Nature Limited 2024. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.Experimental particle physics; Particle astrophysics; Quantum physicsJournal article10.1038/s41567-024-02436-w2024-10-11689583Bacchi, S. [0000-0001-5130-8628]