Many-body interferometry of magnetic polaron dynamics

Abstract

The physics of quantum impurities coupled to a many-body environment is among the most important paradigms of condensed matter physics. In particular, the formation of polarons, quasiparticles dressed by the polarization cloud, is key to the understanding of transport, optical response, and induced interactions in a variety of materials. Despite recent remarkable developments in ultracold atoms and solid-state materials, the direct measurement of their ultimate building block, the polaron cloud, has remained a fundamental challenge. We propose and anlalyze a unique platform to probe time-resolved dynamics of polaron-cloud formation with an interferometric protocol. We consider an impurity atom immersed in a two-component Bose-Einstein condensate, where the impurity generates spin-wave excitations that can be directly measured by the Ramsey interference of surrounding atoms. The dressing by spin waves leads to the formation of magnetic polarons and reveals a unique interplay between few-and many-body physics that is signified by single-and multi-frequency oscillatory dynamics corresponding to the formation of many-body bound states. Finally, we discuss concrete experimental implementations in ultracold atoms. PACS numbers: 67.85.-d arXiv:1701.01454v3 [cond-mat.quant-gas]

Theory of excitation of Rydberg polarons in an atomic quantum gas

“…We note that the physics of the Rydberg oligomer states is different from that of Efimov states in the Bose polaron problem [15,[17][18][19]. While Efimov states are also multibody bound states, they arise due a quantum anomaly of the underlying quantum field theory [20][21][22].…”

“…The calculation of a s,eff from V Ryd (r) [Eq. (18)] could also account for some of this discrepancy through approximations made to describe the Rydberg-atom potential at short range. Residual deviations in the description of the short-range details of the Rydberg molecular potential lead, for instance, also to the minor discrepancies between the FDA and CMC simulation of the Rydberg response from the center of the atomic cloud, shown in Fig.…”

Cold hybrid ion-atom systems

“…II.E). Polarons are attracting increasingly large interest in the ultracold quantum matter community (Ardila and Giorgini, 2016;Ashida et al, 2018;Camargo et al, 2018;Casteels et al, 2013;Guenther et al, 2018;Hu et al, 2016;Jørgensen et al, 2016;Levinsen et al, 2015;Parisi and Giorgini, 2017;Schmidt et al, 2016Schmidt et al, , 2018bShchadilova et al, 2016) as the simplest example of nontrivial quantum field theory. In this arena, ion-atom systems could provide new insight into the problem, especially in the strong coupling regime (Casteels et al, 2011;Grusdt et al, 2017;Schurer et al, 2017;Tempere et al, 2009), as well as allow to study the effects of long-range interactions.…”

Critical slowdown of non-equilibrium polaron dynamics

“…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. While most of previous efforts have been directed towards the equilibrium properties of the Bose polaron, its dynamics has spawned theoretical work only recently [31][32][33][34][35][36], predicting the formation of phonon-impurity bound states for strongly interacting systems [31] and studying trajectories and momentum relaxation of moving impurities [32][33][34][35], as well as the dynamics of phonon dressing in spinor condensates [36].…”