A Quantum Degenerate Gas of Cs

Pierre Desbiolles, Johannes Söding, David Guéry-Odelin +1 more

B. J. DeSalvo, Krutik Patel, Jacob Johansen +1 more

We report on the formation of a stable quantum degenerate mixture of fermionic ^{6}Li and bosonic ^{133}Cs in an optical trap by sympathetic cooling near an interspecies Feshbach resonance. New regimes of quantum degenerate Bose-Fermi mixtures are identified. With moderate attractive interspecies interactions, we show that a degenerate Fermi gas of Li can be fully confined in a Cs Bose-Einstein condensate without external potentials. For stronger attraction where mean-field collapse is expected, no such instability is observed. Potential mechanisms to explain this phenomenon are discussed.

Juha Javanainen

Roberto Onofrio, Luca Salasnich

Juha Javanainen

Daniel Mayer, Felix Schmidt, Daniel Adam +6 more

Abstract We report on the experimental doping of a 87 Rubidium (Rb) Bose–Einstein condensate (BEC) with individual neutral 133 Cesium (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.