Trap induced broadening in a potential hydrogen lattice clock

TL;DR

This paper investigates the use of optical traps for atomic hydrogen clocks, revealing that trap-induced broadening due to ionisation can be mitigated by the hydrogen atom's low mass, enabling high-precision measurements.

Contribution

It predicts three new magic wavelengths for the 1S--2S transition and analyzes trap-induced broadening effects in hydrogen lattice clocks.

Findings

Three new magic wavelengths identified for hydrogen 1S--2S transition.

Trap-induced broadening can be mitigated by low atomic mass enabling Lamb-Dicke confinement.

Hydrogen lattice clock could achieve an intrinsic linewidth of around 1 kHz.

Abstract

We consider the potential use of optical traps for precision measurements in atomic hydrogen (H). Using an implicit summation method, we calculate the atomic polarisability, the rates of elastic/inelastic scattering and the ionisation rate in the wavelength range 395 to 1000 nm. We extend previous work to predict three new magic wavelengths for the 1S--2S transition. At the magic wavelengths, the 1S--2S transition is unavoidably and significantly broadened due to trap-induced ionisation associated with the high intensity required to trap the 1S state. However, we also find that this effect is partially mitigated by the low mass of H, which increases the trap frequency, enabling Lamb-Dicke confinement in shallow lattices. We find that a H optical lattice clock, free from the motional systematics which dominate in beam experiments, could operate with an intrinsic linewidth of O(1 kHz). Trap-induced losses are shown not to limit measurements of other transitions.