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A: Fachverband Atomphysik

A 13: Quantum Gases and Matter Waves (joint session Q/A)

A 13.1: Poster

Dienstag, 21. September 2021, 16:30–18:30, P

Coherent and dephasing spectroscopy for single-impurity probing of an ultracold bath — •Daniel Adam, Quentin Bouton, Jens Nettersheim, Sabrina Burgardt, and Artur Widera — Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, Germany

Individual impurities immersed in a gas form a paradigm of open quantum systems. Especially, nondestructive quantum probing has gained significant interest in recent years. Here, we report on probing the coherent and dephasing dynamics of single impurities in a bath to extract information about the impurity's environment. Experimentally, we immerse single Cs atoms into a Rb bath and perform a Ramsey spectroscopy on the Cs clock transition. The Ramsey fringe is modified by a differential shift of the collisional (kinetic) energy when the two Cs states superposed interact with the Rb bath. The shift is affected by the bath density and the details of the Rb-Cs interspecies scattering length. By preparing the system close to a low-magnetic field Feshbach resonance, we enhance the dependence on the temperature due to the strong dependence of the s-wave scattering length on the collisional energy. By analyzing the coherent phase evolution and decay of the Ramsey fringe contrast, we probe the Rb cloud's density and temperature with minimal perturbation of the cloud.