Tunable Polarons in Bose-Einstein Condensates

Abstract

A toolbox for the quantum simulation of polarons in ultracold atoms is presented. Motivated by the impressive experimental advances in the area of ultracold atomic mixtures, we theoretically study the problem of ultracold atomic impurities immersed in a Bose-Einstein condensate mixture (BEC). The coupling between impurity and BEC gives rise to the formation of polarons whose mutual interaction can be effectively tuned using an external laser driving a quasi-resonant Raman transition between the BEC components. Our scheme allows one to change the effective interactions between polarons in different sites from attractive to zero. This is achieved by simply changing the intensity and the frequency of the two lasers. Such arrangement opens new avenues for the study of strongly correlated condensed matter models in ultracold gases.

Critical slowdown of non-equilibrium polaron dynamics

“…Experiments on imbalanced Fermi gases [8][9][10][11][12] provide an ideal quantum simulation platform for the Fermi polaron [13][14][15]. At the same time, the possibility to realize so-called Bose polarons in atomic Bose-Einstein condensates (BECs) [16,17] has raised further questions and ushered in new theoretical investigations [18][19][20][21][22][23][24][25][26][27][28][29][30], expanding our understanding of quantum impurity physics. The properties of the Bose polaron is arguably closer to the generic solid-state polaron, since the surrounding BEC has a linear low energy dispersion in analogy with acoustic phonons in a solid.…”

Breathing modes of repulsive polarons in Bose-Bose mixtures

“…The single particle Hamiltonian for the condensates and the impurities are defined, respectively by h sp j = −(h 2 /2m j )∇ 2 + V j and h sp I = −(h 2 /2m I )∇ 2 + V I , where V j (x) and V I (x) are respectively, the Bose mixture and the impurity trapping potentials. The coefficient g Ij stands for the impurity-boson interaction which can be determined numerically [10,46,57]. Setting g Ij = 0, Eqs.…”

“…impurity atoms immersed in a binary BEC, has not been addressed except the work of Ref. [46]. Polarons in binary condensates allow us to understand, in useful manner, the intriguing * a.boudjemaa@univ-chlef.dz coupling between the impurities and the two condensates in the phenomenon of phase separation.…”

Polaron Problems in Ultracold Atoms: Role of a Fermi Sea across Different Spatial Dimensions and Quantum Fluctuations of a Bose Medium

“…The corresponding impact on the medium atoms due to the presence of strong impurity-bath correlations is under active investigation [51]. In the case of Bose polarons [7][8][9][10][11][12][58][59][60], the influence of the impurities on their environment (BEC) is more pronounced when compared to Fermi polarons due to the absence of the Pauli blocking effect. Characteristic examples, here, constitute the self-localization [61][62][63][64][65] and temporal orthogonality catastrophe [21] phenomena as well as complex tunneling [66][67][68][69] and emergent relaxation processes [56,70].…”