Controlled doping of a bosonic quantum gas with single neutral atoms (A4)

Daniel Mayer, Felix Schmidt, Daniel Adam, Steve Haupt, Jennifer Koch, Tobias Lausch, Jens Nettersheim, Quentin Bouton, and Artur Wider:

Journal of Physics B: Atomic, Molecular and Optical Physics 52 015301 (2018)

🔓 arXiv:1805.01313 (2018)

We report on the experimental doping of a 87Rubidium (Rb) Bose–Einstein condensate (BEC) with individual neutral 133Cesium (Cs) atoms. We discuss the experimental tools and procedures to facilitate Cs-Rb interaction. First, we use degenerate Raman side-band cooling of the impurities to enhance the immersion efficiency for the impurity in the quantum gas. We identify the immersed fraction of Cs impurities from the thermalization of Cs atoms upon impinging on a BEC, where elastic collisions lead to a localization of Cs atoms in the Rb cloud. Second, further enhancement of the immersion probability is obtained by localizing the Cs atoms in a species-selective optical lattice and a subsequent transport into the Rb cloud. Here, impurity-BEC interaction is monitored by position and time-resolved three-body loss of Cs impurities immersed into the BEC. This combination of experimental methods allows for the controlled doping of a BEC with neutral impurity atoms, paving the way to impurity aided probing and coherent impurity-quantum bath interaction.