Polaron in the dilute critical Bose condensate

Abstract

The properties of impurity immersed in the dilute D-dimensional Bose gas at temperatures close to the second-order phase transition point are considered. Particularly by means of the 1/N -expansion we calculated the leading-order polaron energy and the damping rate in the limit of vanishing boson-boson interaction. It is show that the perturbative effective mass and the quasiparticle residue diverge logarithmically in the long-length limit signalling the non-analytic behavior of impurity spectrum and a non-pole structure of a polaron Green's function in the infrared region, respectively.

Large-N properties of a non-ideal Bose gas

“…[37], but is far from the values 0.3485 (2) [38] and 0.3486(1) [39] obtained for a single-component Bose system's universality class in Monte Carlo simulations. These findings, however, together with the value of the Fisher exponent η = 4/(3N π 2 ) [8,40] obtained with the same accuracy determine the critical behavior of the three-dimensional Bose system in the large-N limit.…”

Static Impurities in a Weakly Interacting Bose Gas

“…The experimental progress in the field of ultra-cold atomic gases has recently lead to the observation [24] of Bose polarons at finite temperatures. This experiment confirmed previous theoretical predictions [25][26][27][28][29][30] about the breakdown of the quasi-particle picture description of Bose polarons in a close vicinity of the Bose-Einstein condensation (BEC) point.…”

Variational Approach for Impurity Dynamics at Finite Temperature

“…Second, one often needs to perform a thermal average over the impurity's dynamical degrees of freedom (such as the initial impurity momenta in the case of mobile impurities). Therefore, theoretical works on Fermi and Bose polarons at finite temperature in three dimensions have, thus far, been restricted to pinned impurities [29][30][31], weak impurity-medium interactions [32,33], the virial expansion [34], and approximate diagrammatic approaches [35][36][37]. Most notably, there are no exact Monte Carlo approaches for such finite-temperature polarons, thus emphasizing the need for alternative methods.…”