Stephen Hogan (UCL)

Atomic beam sources and quantum sensors for absolute neutrino mass and antimatter gravity

Methods of precision measurement and quantum sensing from AMO physics, are being increasingly deployed for new tests of fundamental physics. In this talk, I will discuss two particular examples of this use of atomic quantum technologies for fundamental physics. The first relates to the determination of the absolute neutrino mass from the beta-decay-electron spectrum of atomic tritium. The second involves a test of antimatter gravity, and the Weak Equivalence Principle (WEP), for purely leptonic positronium (Ps) atoms.

The neutrino mass measurements require the development of cold, high-phase-space density sources of atomic hydrogen isotopes (H, D and ultimately T) and confinement of these ground-state atoms using inhomogeneous magnetic fields. They will also benefit from the use of atoms in Rydberg states as quantum sensors for in situ magnetic and electric field mapping in the cryogenic environment of an electron spectrometer in which electron energies are determined from the frequency of the cyclotron radiation they emit as they orbit in a homogeneous magnetic field. Tests of antimatter gravity and the WEP with Ps have motivated the development of an approach to atom-interferometry that can be implemented with Ps atoms in high Rydberg states that decay slowly by spontaneous emission rather than self annihilation. I will describe the work carried out in my laboratory in each of these areas.