2014/11/30 by Peter Kroiss, Peter Kroiß, Lode Pollet · 35 citations
Mathematics · Physics and Astronomy · #Atomic physics #Cold Atom Physics and Bose-Einstein Condensates #Condensed matter physics #Effective mass (spring–mass system) #Electron #Excited state #Feynman diagram #Mathematics #Monte Carlo method #Phase (matter) #Phase diagram #Physics #Physics of Superconductivity and Magnetism #Polaron #Quantum many-body systems #Quantum mechanics #Quasiparticle #Superconductivity #cond-mat.quant-gas
paper · pdf · doi:10.1103/physrevb.91.144507
published in Physical Review B 91(14) (American Physical Society) · 11 pages, 18 figures, replaced with published version
openalex publication_date 2015/04/20 · arxiv created 2015/04/22 · arxiv updated 2015/04/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We apply the diagrammatic Monte Carlo approach to three-dimensional Fermi-polaron systems with mass imbalance, where an impurity interacts resonantly with a noninteracting Fermi sea whose atoms have a different mass. This method allows us to go beyond frequently used variational techniques by stochastically summing all relevant impurity Feynman diagrams up to a maximum expansion order limited by the sign problem. Polaron energy and quasiparticle residue can be accurately determined over a broad range of impurity masses. Furthermore, the spectral function of an imbalanced polaron demonstrates the stability of the quasiparticle and allows us to locate in addition also the repulsive polaron as an excited state. The quantitative exactness of two-particle-hole wave functions is investigated, resulting in a relative lowering of polaronic energies in the mass-imbalance phase diagram. Tan's contact coefficient for the mass-balanced polaron system is found in good agreement with variational methods. Mass-imbalanced systems can be studied experimentally by ultracold atom mixtures such as 6Li\ensuremath-40K.