Adaptive feedback normally provides the greatest accuracy for optical phase
measurements. New advances in nitrogen vacancy centre technology have enabled
magnetometry via individual spin measurements, which are similar to optical
phase measurements but with low visibility. The adaptive measurements that
previously worked well with high-visibility optical interferometry break down
and give poor results for nitrogen vacancy centre measurements. We use advanced
search techniques based on swarm optimisation to design better adaptive
measurements that can provide improved measurement accuracy with low-visibility
interferometry, with applications in nitrogen vacancy centre magnetometry.Comment: 8 pages, 7 figures, comments welcom