Improving the Dynamic Range of Interacting Quantum Sensors via Optimized Quantum Control

원문 초록

Interacting spin ensembles are promising platforms for quantum sensing, but spin-spin interactions can induce complex, nonmonotonic responses to external fields, limiting the dynamic range over which the fields can be estimated unambiguously. Here, we propose a quantum-circuit-learning-inspired method to improve the dynamic range of interacting quantum sensors using optimized global control fields. We consider an ensemble of dipole-coupled spins subjected to an inhomogeneous magnetic field generated by an electric current. By optimizing the global control fields applied during sensing, we train the expectation value of the collective magnetization to approximate a prescribed monotonic target function. We also introduce a penalty on the magnetization variance to account for measurement fluctuations. Numerical simulations demonstrate that the optimized control can substantially enlarge the dynamic range compared with sensing without control. We further investigate the trade-off between dynamic range and estimation uncertainty and show that the variance penalty can reduce the uncertainty at the expense of dynamic range. These results demonstrate that learning-assisted global control provides a promising approach to improving the performance of interacting quantum sensors.