2017/08/31 by Nils-Eric Guenther, Pietro Massignan, Maciej Lewenstein +1 · 1 citation
Physics and Astronomy · #cond-mat.quant-gas
paper · pdf · doi:10.1103/physrevlett.120.050405
published as Phys. Rev. Lett. 120, 050405 (2018) · 4 pages, 5 figures
arxiv created 2018/02/01 · arxiv updated 2018/02/08
The temperature dependence of a mobile impurity in a dilute Bose gas, the Bose polaron, is investigated for wide a range of impurity-bath interactions. Using a diagrammatic resummation scheme designed to include scattering processes important at finite temperature T, we show that the phase transition of the environment to a Bose-Einstein condensate at the critical temperature Tc leads to several non-trivial effects. The attractive polaron present at T=0 fragments into two quasiparticle states for finite temperature whenever |a|\gtrsim aB, with a and aB the impurity-boson and boson-boson scattering lengths. While the quasiparticle with higher energy disappears at Tc, the ground state quasiparticle remains well-defined across Tc. Its energy depends non-monotonically on temperature, featuring a minimum at Tc, after which it increases towards zero, and at T≫ Tc the polaron eventually becomes overdamped due to strong scattering with thermally excited bosons.