Improving the performance of cold-atom inertial sensors and gravimeters using robust control

Large momentum transfer (LMT) atom-optical beamsplitters and mirrors—implemented via Bragg diffraction—increase the space-time area enclosed by atom interferometers, offering a promising means of improving the precision of cold-atom inertial sensors. However, to date LMT has not improved absolute cold-atom inertial sensitivity, due to the stringent velocity-selectivity of LMT Bragg pulses making high contrast atom interferometry with appreciable atomic flux extremely challenging. In this work, I will present theoretical and experimental results showing how error-robust quantum control can be used to overcome these traditional limitations on LMT Bragg atom interferometry. Our unique approach to quantum hardware optimisation and operation allows us to design LMT pulses with increased velocity acceptance and improved robustness to laser intensity inhomogeneity. We demonstrate that our control solutions provide > 10X improvement in measurement sensitivity over Gaussian Bragg pulses at 102 ?k momentum separations, and further enable operation at longer interrogation times and without velocity selection of the initial cold thermal atomic source. Our results show how quantum control at the software level can improve future cold-atom inertial sensors, enabling new capabilities in navigation, hydrology, and space-based gravimetry.