



01577nas a2200157   4500008004100000245004200041210004200083260001400125520114200139100001701281700002301298700001801321700002401339700001901363856003701382       2020                        eng d00aOptimal control for quantum detectors0 aOptimal control for quantum detectors  c5/12/20203 a<p>Quantum systems are promising candidates for sensing of weak signals as they can provide unrivaled performance when estimating parameters of external fields. However, when trying to detect weak signals that are hidden by background noise, the signal-to-noise-ratio is a more relevant metric than raw sensitivity. We identify, under modest assumptions about the statistical properties of the signal and noise, the optimal quantum control to detect an external signal in the presence of background noise using a quantum sensor. Interestingly, for white background noise, the optimal solution is the simple and well-known spin-locking control scheme. We further generalize, using numerical techniques, these results to the background noise being a correlated Lorentzian spectrum. We show that for increasing correlation time, pulse based sequences such as CPMG are also close to the optimal control for detecting the signal, with the crossover dependent on the signal frequency. These results show that an optimal detection scheme can be easily implemented in near-term quantum sensors without the need for complicated pulse shaping.</p>1 aTitum, Paraj1 aSchultz, Kevin, M.1 aSeif, Alireza1 aQuiroz, Gregory, D.1 aClader, B., D.  uhttps://arxiv.org/abs/2005.05995