Optimizing quantum sensors to their ultimate precision limits

ANALIA ZWICK

Workshop; Quantum foundation and quantum information; 2019

Precise probing of quantum systems is one of the key to progress indiverse quantum technologies, including quantum sensing andmetrology, quantum information processing and quantum many bodymanipulations. Controlled quantum spins are sensitive probes of theenvironment and a powerful tool for characterizing highly-complexquantum systems at a molecular-scale. We explore the ability of a qubit-probe to characterize unknown parameters of its environment. Byresorting to quantum estimation theory, we analytically find the ultimatebound on the precision of estimating key parameters of a broad class ofubiquitous environmental noises which the qubit may probe. Byoptimizing the dynamical control on the probe under realistic constraintsone may attain the maximal accuracy bound on the estimation of theseparameters by the least number of measurements possible. Applicationsof this protocol to quantum sensing are illustrated for quantum qubit-probes serving as thermometers and sensors for imaging or monitoringbiological process.