Deep-Lattice Bloch-Band Interferometry for Inertial Sensing
Christian Ordetx
Abstract
Atom interferometers exploit the wave nature of matter to measure inertial forces with high precision, but conventional light-pulse implementations typically require large free-fall distances and complex optical systems. Bloch-band interferometry offers an alternative architecture in which atoms remain confined within an optical lattice and interferometric operations are implemented through controlled transitions between Bloch bands. This thesis investigates Bloch-band interferometry with particular emphasis on robustness to phase decoherence and operation in the deep-lattice regime. The work begins with multi-well models that provide intuition for tunneling, interference, and phase coherence. Phase scrambling was introduced to model loss of coherence, demonstrating that interference contrast is reduced but not eliminated. These insights motivated a full momentum-space simulation of a Bloch-band Michelson interferometer, including splitting, transport, reflection, and recombination. Acceleration scans with site-to-site phase randomness showed that interferometric fringes and sensitivity persist even with reduced coherence. Building on this robustness, Bloch-band interferometry was extended to a deep optical lattice with depth of 27 times the recoil energy. Higher Bloch bands were used to define interferometric pathways, and machine-learned shaking functions were implemented to realize beamsplitter and mirror operations. The resulting deep-lattice interferometer exhibits acceleration-dependent population fringes and measurable sensitivity. To our knowledge, this work presents the first exploration of Bloch-band interferometry in the deep-lattice regime and demonstrates the first realization of a deep-lattice Bloch-band interferometer for inertial sensing. These results suggest that Bloch-band interferometry can remain operational in regimes approaching the insulating limit, providing a potential route toward compact and robust quantum inertial sensors.