Impurity transport through a strongly interacting bosonic quantum gas

Abstract

Using near-exact numerical simulations we study the propagation of an impurity through a onedimensional Bose lattice gas for varying bosonic interaction strengths and filling factors at zero temperature. The impurity is coupled to the Bose gas and confined to a separate tilted lattice. The precise nature of the transport of the impurity is specific to the excitation spectrum of the Bose gas which allows one to measure properties of the Bose gas non-destructively, in principle, by observing the impurity; here we focus on the spatial and momentum distributions of the impurity as well as its reduced density matrix. For instance we show it is possible to determine whether the Bose gas is commensurately filled as well as the bandwidth and gap in its excitation spectrum. Moreover, we show that the impurity acts as a witness to the cross-over of its environment from the weakly to the strongly interacting regime, i.e., from a superfluid to a Mott insulator or TonksGirardeau lattice gas and the effects on the impurity in both of these strongly-interacting regimes are clearly distinguishable. Finally, we find that the spatial coherence of the impurity is related to its propagation through the Bose gas, giving an experimentally controllable example of noise-enhanced quantum transport.

Orthogonality catastrophe as a consequence of qubit embedding in an ultracold Fermi gas

“…(8). Using, for example, resonance fluorescence techniques, P g (t,φ) can be measured for various values of the phase φ and thus fitted to Eq.…”

“…In these, two separate, ultracold atomic systems are combined in such a way that their coupling can be externally controlled and their states independently measured, thus allowing detailed investigations into the theory of quantum interactions and decoherence. Existing examples of such systems are single spin impurities embedded in ultracold Fermi gases [2,3] and the combination of neutral [4][5][6][7][8] or charged single atoms [9,10] with Bose-Einstein condensates. These experiments offer the possibility for controlled simulation of many different system-environment models synonymous with condensedmatter physics and nonequilibrium statistical physics [11].…”

Bloch oscillations of bosonic lattice polarons

“…Additionally, cold-atomic ensembles are well suited to the investigation of nonequilibrium phenomena [39][40][41][42][43] since they are very well isolated from the environment and their parameters can be tuned dynamically. There is thus a growing interest in out-of-equilibrium polaron problems [23,37,37,38,[44][45][46][47][48][49] which remained out of reach in solid-state systems due to short equilibration times.…”

Optical lattices with large scattering length: Using few-body physics to simulate an electron-phonon system

“…A traditional way of simulating electron-phonon systems with cold atoms is to trap the species representing electrons in an OL and place it in contact with the Bose condensate of another species that provides the phonons [9][10][11][12][13][14][15]. In our case the trapped species represents the ions providing the phonons and the untrapped species represents the electrons.…”