Optimal frequency estimation and its application to quantum dots

Peter Stano
Center for Emergent Matter Science, RIKEN, Saitama, Japan

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We address the interaction-time optimization for frequency estimation in a two-level system. The goal is to track with maximum precision a stochastic perturbation. Our approach is valid for any figure of merit used to define optimality, and is illustrated for the variance and entropy. For the entropy, we clarify the connection to maximum-likelihood estimation. We devise novel estimation protocols with and without feedback. They outperform common protocols given in the literature. We design a probabilistic self-consistent protocol as an optimal estimation without feedback. It can improve current experimental techniques and boost coherence times in quantum computing.