coLd hydrOgen GravItational Quantum States – LOGIQS

Our first goal is to observe Gravitational Quantum States (GQS) of Hydrogen atoms, to test in the future new physics such as extra fundamental short-range interactions or probing the weak equivalent principle in quantum regime. The GQS are realized with particles trapped in the gravitational field (top confinement), bouncing onto a
surface, thanks to Quantum Reflections (QRs) (bottom confinement). QRs are driven by the surface’s potential and the vertical particle’s velocity, without any contact to the surface occurring. GQS has been formed with neutrons at ILL (France) [1], but never with atoms. We aim here to observe for the first time GQS of Hydrogen, using a similar setup as the historical neutron experiment. This experiment is part of a new international collaboration GRASIAN (https://grasian.eu) and will be set at ETH Zurich (Switzerland).

The second step will be to observe the quantized free fall (QFF) of H which will serve as a proof of principle for future measurements with anti-H as planned by the GBAR experiment [2]. This would allow to push the precision on the measurement of the effect of gravity for antimatter by 3-4 orders of magnitude [3] compared to the original GBAR proposal, that aims to probe the acceleration of antihydrogrens in the Earth gravity field by measuring its free fall. A prototype of the future experiment will be designed and developed at LKB, before being implemented at ETH.

[1] V.V. Nesvizhevsky et al, Quantum states of neutrons in the Earth’s gravitational field, Nature 415 (2002) 297.
[2] P. Perez et al. The GBAR antimatter gravity experiment. Hyperfine Interact., 233(1-3):21–27, 2015.
[3] P.P. Crepin, C. Christen, R. Guerout, V.V. Nesvizhevsky, A.Yu. Voronin, and S. Reynaud. Quantum interference test of the equivalence principle on antihydrogen. Phys. Rev. A, 99:042119, 2019.