Single-shot holographic readout of an atom interferometer

• Main Author: MacKellar, Andrew Rae
• Published: University of Strathclyde 2018
• Subjects: 530
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.742063

Atom interferometry is a precision measurement technique that encodes information in the phase of atomic wavefunctions, using matter-wave interference to project the encoded phase information onto some relatively easy-to-measure property at the interferometer output, like the fractional atomic population in a specific momentum or internal state. Atoms are perturbed by influences to which photons are insensitive, offering atom interferometers excellent sensitivity and access to physics outwith the range of conventional optical interferometers. As such, for probing of fundamental physics such as QED corrections, atoms are an obvious test bed. The primary focus of this thesis is the construction and development of an atom interferometer capable of performing single-shot measurements of the fine-structure constant using a holographic readout technique. This achievement allows the holographic interferometer an increased data acquisition rate on the order of 700-times that [sic] a conventional configuration. As an interfering medium we use a Bose-Einstein condensate containing around ~10[to the power of]5 87Rb atoms. We coherently manipulate the momentum of these atoms with the scattering of photons from an optical lattice with fully controllable intensity. We have developed a numerical toolbox capable of calculating optical-lattice pulse-sequences to generate arbitrary atom-optical operations such as mirrors, and beam-splitters, experimentally demonstrated with an efficiency of 99:97±0:03%. We have used these atom optics to create experimental atom interferometers with various applications, shown here in the cases of a magnetic gradiometer and in measurements of recoil frequency. This latter configuration has been used to perform a measurement of the fine-structure constant with a fractional uncertainty of 6500 ppm in a single shot, with a clear pathway to reduce this uncertainty to 2300 ppm per shot, whilst the increased speed of the holographic interferometer allows a corresponding reduction in uncertainty to 60 ppm within a twelve hour integration period.