Interactions of Ultracold Impurity Particles with Bose-Einstein Condensates.

摘要

Research on interactions between quantum gases and impurities has become an active area of AMO. Here, two setups have been constructed and operated towards these goals. In the first, a metal tip (diameter 125 microns) is mounted close to a magneto-optic trap (MOT). Rydberg excitations are implanted in a cold-atom region (diameter about 10 microns, length about 50 microns). Interactions between the excitations cause excitation blockades, short- and medium-range order, as well as dynamics due to van-der-Waals interaction. All these topics were studied. The second setup is a double-trap system, in which magnetically trapped rubidium atom samples are prepared between 1 and 10 micro-Kelvin temperature and densities of about 10^12 cm^-3. Cold circular Rydberg atoms have been prepared and trapped. The dynamics of these highly dipolar atoms in the magnetic trap was studied, and collision-induced loss was observed and traced back to collisions between the long-lived circular atoms and cold ground state atoms. Novel D-type molecules between Rydberg and ground-state atoms were realized. These molecules are due to an attractive triplet s-wave low-energy electron scattering interaction. Five papers were published [two Phys. Rev. Lett, 2 Phys. Rev. A] and one submitted to PRL.