Ultra-Dilute Gas of Polarons in a Bose–Einstein Condensate

Abstract

We investigate the properties of a dilute gas of impurities embedded in an ultracold gas of bosons that forms a Bose–Einstein condensate (BEC). This work focuses mainly on the equation of state (EoS) of the impurity gas at zero temperature and the induced interaction between impurities mediated by the host bath. We use perturbative field-theory approaches, such as Hugenholtz–Pines formalism, in the weakly interacting regime. In turn, for strong interactions, we aim at non-perturbative techniques such as quantum–Monte Carlo (QMC) methods. Our findings agree with experimental observations for an ultra dilute gas of impurities, modeled in the framework of the single impurity problem; however, as the density of impurities increases, systematic deviations are displayed with respect to the one-body Bose polaron problem.

Strongly Interacting Bose Polarons in Two-Dimensional Atomic Gases and Quantum Fluids of Polaritons

“…These studies include the experimental realization of the Bose polaron in the presence of a Feshbach resonance [15][16][17], the dynamical formation of the polaron [18], and critical aspects of the polaron [19]. The nature of the strongly interacting polaron unveiled a plethora of phenomena [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34], paving the way for the study of the Bose polaron beyond the single impurity limit [35][36][37][38][39][40][41][42][43][44][45][46], dipolar polarons [47], and charged polarons in the atomic context [48][49][50][51][52], among others.…”

Many-body bound states and induced interactions of charged impurities in a bosonic bath

“…In the future, it will be interesting to investigate the impact of the ion motion degrees of freedom both on the ground state and transport properties, especially in the many-body bound state regime. Furthermore, the role of larger ionic chains and the possibility of multipolarons states 67,68 in hybrid atom-ion systems may also be an interesting path to explore. Finally, an important issue is finite temperature effects and how thermal fluctuations affect our findings.…”

Many-body bound states and induced interactions of charged impurities in a bosonic bath

“…In the future, it will be interesting to investigate the impact of the ion motion degrees of freedom both on the ground state and transport properties, especially in the many-body bound state regime. Furthermore, the role of larger ionic chains and the possibility of multipolarons states [79] in hybrid atom-ion systems may also be an interesting path to explore. Finally, an important issue is finite temperature effects and how thermal fluctuations affect our findings.…”