title: Impurity in a Bose-Einstein Condensate and the Efimov Effect.
abstract: We investigate the zero-temperature properties of an impurity particle interacting with a Bose-Einstein condensate (BEC), using a variational wave function that includes up to two Bogoliubov excitations of the BEC. This allows one to capture three-body Efimov physics, as well as to recover the first nontrivial terms in the weak-coupling expansion. We show that the energy and quasiparticle residue of the dressed impurity (polaron) are significantly lowered by three-body correlations, even for weak interactions where there is no Efimov trimer state in a vacuum. For increasing attraction between the impurity and the BEC, we observe a smooth crossover from atom to Efimov trimer, with a superposition of states near the Efimov resonance. We furthermore demonstrate that three-body loss does not prohibit the experimental observation of these effects. Our results thus suggest a route to realizing Efimov physics in a stable quantum many-body system for the first time.
authors.affiliation: School of Physics and Astronomy, Monash University, Victoria 3800, Australia.
authors.forename: Jesper
authors.initials: J
authors.lastname: Levinsen
authors.affiliation: School of Physics and Astronomy, Monash University, Victoria 3800, Australia.|London Centre for Nanotechnology, Gordon Street, London WC1H 0AH, United Kingdom.
authors.forename: Meera M
authors.initials: MM
authors.lastname: Parish
authors.affiliation: Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark.
authors.forename: Georg M
authors.initials: GM
authors.lastname: Bruun