Neutrino Oscillations and Gravity: Testing the Uncertainty Principle Experimentally.

Research demonstrates that modifications to the Heisenberg uncertainty principle, linked to gravity, alter predicted neutrino oscillation probabilities via a phase term dependent on neutrino mass. These alterations, modelled using parity-time symmetric mechanics, may be detectable in experiments like DUNE and JUNO, and verifiable using analogue quantum systems.

The subtle transformations of neutrinos, elusive subatomic particles, may hold a key to understanding the interplay between quantum mechanics and gravity. Researchers are investigating how modifications to the fundamental principles of quantum uncertainty, stemming from theories of quantum gravity, impact neutrino flavour oscillation – the process by which neutrinos change ‘flavour’ as they travel. A new theoretical study, detailed in the article ‘Probing Planck scale effects on absolute mass limit in neutrino flavour evolution’, explores these potential effects using a framework known as parity-time (PT) symmetric mechanics, which allows for the modelling of non-Hermitian quantum systems.

Kartik Joshi from the Indian Institute of Science Education and Research Mohali, Sanjib Dey from the Birla Institute of Technology and Science, Pilani, and Satyajit Jena, also from the Indian Institute of Science Education and Research Mohali, present their findings, suggesting that current and future neutrino experiments – including DUNE, JUNO, IceCube, and KATRIN – may be sensitive to these subtle quantum gravitational signatures, and that analogous tests are possible using cold atom, trapped ion, and photonic platforms.

Neutrino oscillations, the spontaneous transformation of neutrino flavour during propagation, offer a potential window into the intersection of quantum gravity and particle physics. Current research investigates how alterations to the Heisenberg uncertainty principle – a cornerstone of quantum mechanics stating fundamental limits to the precision with which certain pairs of physical properties can be known – may manifest in these subtle particle transformations.

This work extends the standard two-flavour neutrino model – a simplified representation of neutrino behaviour focusing on two of the three known neutrino types – by incorporating novel phase terms. These terms are dependent on the square roots of neutrino masses and predict observable features that extend beyond those explained by conventional mass-squared differences, which currently account for the observed oscillation patterns.

The resulting theoretical framework introduces non-Hermitian dynamics – a mathematical description where the usual rules of quantum mechanics are relaxed – which are addressed through the application of parity-time (PT) symmetric mechanics. PT symmetry is a branch of quantum mechanics that enables the consistent description of systems exhibiting balanced gain and loss, providing a means to address the non-Hermitian nature of the modified neutrino model.

Detailed analyses indicate the potential for observing these effects in current and forthcoming neutrino experiments. Sensitivity assessments focus on facilities such as the Deep Underground Neutrino Experiment (DUNE), the Jiangmen Underground Neutrino Observatory (JUNO), the IceCube Neutrino Observatory, and the Karlsruhe Tritium Neutrino Experiment (KATRIN).