Abstracts Physics

Towards mobile quantum sensors for gravity surveys

by Alexander Niggebaum

Design and first characterisations of the mobile sensor head in the Gravity Gradient Technologies and Opportunities Programme (GGtop) are presented. The aim of the project is the development of a mobile gravity gradiometer and faces the challenge of condensing a normally lab filling experiment in a portable and robust package. A fibre network replaced free space optics light distribution and fibre based components free space equivalents. Although stable against misalignment, the systems performance is limited by polarization changes of the guided light which arise from birefringence fluctuations along the length of the network due to external temperature fluctuations and mechanical disturbances. These instabilities limit the achievable temperature of the trapped rubidium 87 cloud to approx. 18μK. In preparation for gravity measurements, Rabi oscillations and Ramsey fringes with a λ/2 time of 7.4μs were successfully demonstrated in a co-propagating Raman beam configuration. The atom cloud was launched as a first step towards gravity gradiometry. As the system was designed to be portable, the complete system fits into a 1.5m x 2m x 0.5m package, plus a 14u rack of support electronics.