Dynamik in der Quantenmetrology
Messsysteme
Theoretische Physik der kondensierten Materie
Zusammenfassung der Projektergebnisse
The DFG Project "Dynamics in Quantum Metrology" (german title: "Dynamik in der Quantenmetrologie") revealed the potential which lies in improving the dynamics of quantum sensors. The general aim in quantum metrology is to develop sensors which use quantum systems such as atoms or photons and surpass the precision of classical sensors. This project breaks with the conventional ways of achieving quantum enhanced sensors by applying quantum enhancements to the dynamics instead of the initial states. Based on a fundamental insight that both quantum metrology and quantum chaos are characterized by the sensitivity to changes of the dynamics, so-called quantum-chaotic sensors were proposed. Quantum-chaotic sensors achieve an improved sensitivity and avoid typical obstacles of conventional quantum sensors. The merits of quantum-chaotic sensors were demonstrated by simulating a realistic quantum-chaotic atomic-vapor magnetometer which is part of a published patent application. Enhancing the dynamics of quantum sensors beyond the case of quantum-chaotic sensors was approached with reinforcement learning, a machine learning technique. As part of this project, machine learning techniques were also used to improve the Bayesian estimation of parameters from data acquired with quantum sensors. Neural networks were shown to be efficient decision taking tools, so-called heuristics, for adaptively adjusting properties of the quantum sensors in order to enhance the Bayesian estimation. This versatile machine learning method for creating fast and strong heuristics is expected to bring forward the application of Bayesian quantum sensors in quantum technology. Moreover, within this project, proofs for new bounds on measurement precision were given for the case that there is some uncertainty in the initial state of the quantum sensor. Bounds were also given for the case that the dynamics of quantum sensors is optimized. The conditions for reaching these bounds were specified. In comparison with previous bounds, one is now able to estimate the potential of mixed states for quantum sensing more precisely. Future theoretical work in quantum metrology is expected to build upon these general results.
Projektbezogene Publikationen (Auswahl)
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(2018). Quantum metrology with quantum-chaotic sensors. Nature Communications, 9(1):1351
Fiderer, L. J. and Braun, D.
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(2019). Maximal Quantum Fisher Information for Mixed States. Phys. Rev. Lett., 123:250502
Fiderer, L. J., Fraïsse, J. M. E., and Braun, D.
