Mainz 2026 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 36: Poster – Ultra-cold Atoms, Ions and BEC (joint session A/Q)

A 36.35: Poster

Donnerstag, 5. März 2026, 17:00–19:00, Philo 1. OG

Bayesian Optimization of Measurement Protocols for the Thermometry of Ultracold Gases — •Luca Leon Granert, Julian Feß, Sabrina Burgardt, Silvia Hiebel, and Artur Widera — Department of Physics, RPTU University Kaiserslautern-Landau, 67663 Kaiserslautern, Germany

Precise thermometry in ultracold gases is essential for exploring quantum many-body phenomena. Established methods, such as time-of-flight thermometry, lose precision in regimes with weak signals and often destroy the sample. Quantum probes provide a non-destructive approach by encoding environmental information into internal states with minimal disturbance to the system. In this work, spin-based quantum thermometers are realized by immersing individual Cs atoms into an ultracold Rb bath. Inelastic spin-exchange processes between probe and bath transfer motional and thermal information onto the internal spin states. The information gained per inelastic event increases when nonequilibrium spin dynamics are exploited. The optimal parameters for this process depend on the temperature being estimated, making this system well-suited for Bayesian estimation strategies. Three measurement protocols are investigated: an unoptimized, an a priori optimized, and an adaptively optimized version. Their performance is evaluated based on their convergence behavior and achievable estimation accuracy. The a priori optimized protocol shows the best performance in this comparison. These results show that nonequilibrium probe dynamics can enhance quantum thermometry, supporting efficient and precise temperature estimation in ultracold environments.

Keywords: Bayesian Estimation; Quantum Thermometry; Single Atoms; Optimal Probing