Creation of a strontium microtrap: Towards a spin-squeezed atomic clock

Abstract

This thesis details the development of the pre-requisite experimental tools to create
a proof-of-principle spin-squeezed atomic clock based upon an array of individual
strontium atoms using Rydberg-dressed interactions. We experimentally and theoretically
study Rydberg-dressing in a strontium narrow-line MOT, demonstrating
that it is possible to coherently admix a Rydberg state into the narrow intercombination
transitions of strontium. This work is based upon a quantitative semi-classical
Monte-Carlo model of a strontium narrow-line MOT, where the combination of a
quantum treatment of the light scattering process with a Monte-Carlo simulation
of the atomic motion leads to a quantitative description of the spatial, thermal and
temporal dynamics of the narrow-line MOT. By performing calculations of the dynamic
polarisability of all the states relevant to laser cooling strontium, we have
designed and constructed a new experimental apparatus to facilitate the creation of
a microtrap of strontium. We observe and characterise the frst known microtrap
of strontium and outline the next steps towards the creation of an array of single
atoms.

Due to the creation of Rydberg atoms in the strontium microtrap, understanding
ionisation and interaction mechanisms may be of signifcant importance. We therefore
study Rydberg ionisation mechanisms in a thermal beam of strontium atoms
using simultaneous measurements of Rydberg EIT and spontaneously created ions
or electrons. By connecting the optical and electrical signals using the optical Bloch
equations, we are able to determine the dominant ionisation mechanisms of Rydberg
atoms in the thermal beam. We also report the frst observations of optical
and electrical bistability, which may shed further light onto the origin of bistability
in atom vapours.