Robustness of Quantum-Enhanced Adaptive Phase Estimation
This work addresses the practical challenge of selecting robust control policies for quantum metrology in noisy environments, but it is incremental as it focuses on testing and comparison rather than introducing new methods.
The researchers tackled the problem of evaluating the robustness of adaptive quantum-enhanced metrology policies under unknown noise conditions by simulating four phase-noise models, and they developed a test and resource comparison method to assess policy efficacy.
As all physical adaptive quantum-enhanced metrology schemes operate under noisy conditions with only partially understood noise characteristics, so a practical control policy must be robust even for unknown noise. We aim to devise a test to evaluate the robustness of AQEM policies and assess the resource used by the policies. The robustness test is performed on QEAPE by simulating the scheme under four phase-noise models corresponding to normal-distribution noise, random-telegraph noise, skew-normal-distribution noise, and log-normal-distribution noise. Control policies are devised either by an evolutionary algorithm under the same noisy conditions, albeit ignorant of its properties, or a Bayesian-based feedback method that assumes no noise. Our robustness test and resource comparison method can be used to determining the efficacy and selecting a suitable policy.