Towards precision measurement with trapped hydrogen atoms

Abstract

The hydrogen atom (H) is the most theoretically well-understood atomic system of all; boasting analytic solutions to both the Schrödinger and Dirac equations, and calculable QED corrections. As such, precision spectroscopy of H promises to be an excellent probe of fundamental physics, particularly for low-energy tests of QED and fifth force searches. Currently, the H spectral data-set is plagued by internal tension, expressed in the proton charge radius puzzle. There is significant evidence to suggest that this tension is at least partly a result of systematic differences between measurements. Optical trapping has led to significant advances in measurements of other atoms, particularly with the development of optical lattice clocks, where systematics related to atomic motion are tightly controlled. This thesis is concerned with the potential application of optical trapping to precision H spectroscopy towards a resolution of the proton charge radius puzzle. In service of this, it considers the effects of an off-resonant field upon a spectroscopic measurement — taking a potential 1S–2S lattice clock as an example — and whether the proven route to BEC can lead to a Mott insulator (MI) of H that is suitable for spectroscopy. This thesis describes new software for calculating atomic polarisability and atom-photon scattering rates of H S-states; reports new limits on the operation of a H lattice clock, dominated by multi-photon ionisation of the 2S state; and, for the first time, derives the conditions for producing a unitary filling MI of H.