SAMOP 2021 – wissenschaftliches Programm
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QI: Fachverband Quanteninformation
QI 9: Quantum Metrology
QI 9.5: Vortrag
Donnerstag, 23. September 2021, 12:15–12:30, H4
Bayesian Quantum Thermometry — •Julia Boeyens1, Stefan Nimmrichter1, and Stella Seah2 — 1University of Siegen, Siegen 57068, Germany — 2University of Geneva, 1211 Geneva, Switzerland
Most theoretical treatments of temperature estimation in quantum systems have focused on systems in thermal equilibrium in the asymptotic limit of many measurements. In this limit, the thermal Cramér-Rao bound applies, and the optimal measurement strategy can be found by maximizing the Fisher information, either locally for each possible temperature or over a desired temperature range [1]. It has also been shown that driving systems out of thermal equilibrium by means of repeated finite-time collisions with non-thermal probes can boost temperature sensitivity beyond the Cramér-Rao bound in the limit of many repetitions [2]. However, in practical implementations, only scarce data may be available and the Bayesian method of parameter estimation is more appropriate [3]. Here, we study non-informative Bayesian thermometry with a minimal restriction on the allowed temperature range and with a limited number of qubit probes in and out of thermal equilibrium. We compare different estimates for the temperature and the associated error and work out the most faithful estimation strategy. We demonstrate how non-equilibrium thermometry improves measurement precision at high temperatures already for a few hundred qubit probes.
[1] M. Mehboudi, A. Sanpera, L.A. Correa; J. Phys. A 52, 303001 (2019) [2] S. Seah et al; Phys. Rev. Lett. 123, 180602 (2019) [3] J. Rubio, J. Anders, L.A. Correa; arXiv:2011.13018