Bose polarons at finite temperature and strong coupling

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 trans...

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Bibliographic Details
Published inarXiv.org
Main Authors Nils-Eric Guenther, Massignan, Pietro, Lewenstein, Maciej, Bruun, Georg M
Format Paper Journal Article
LanguageEnglish
Published Ithaca Cornell University Library, arXiv.org 01.02.2018
Subjects
Bosons
Critical temperature
Impurities
Phase transitions
Physics - Quantum Gases
Polarons
Scattering
Temperature dependence
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Summary: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 \(T_c\) leads to several non-trivial effects. The attractive polaron present at \(T=0\) fragments into two quasiparticle states for finite temperature whenever \(|a|\gtrsim a_B\), with \(a\) and \(a_B\) the impurity-boson and boson-boson scattering lengths. While the quasiparticle with higher energy disappears at \(T_c\), the ground state quasiparticle remains well-defined across \(T_c\). Its energy depends non-monotonically on temperature, featuring a minimum at \(T_c\), after which it increases towards zero, and at \(T\gg T_c\) the polaron eventually becomes overdamped due to strong scattering with thermally excited bosons.
ISSN:2331-8422
DOI:10.48550/arxiv.1708.08861