In our cold-atom experiments, we study the dynamics of strongly interacting impurity atoms embedded in a one-dimensional (1D) strongly interacting host gas. For accelerated impurity motion we have found some while ago the emergence of Bloch-type oscillations even though no imprinted lattice structure is present [1]. Such motion can be seen as repeated Bragg scattering off the host atoms’ two-point correlation function. The situation is more intricate for the case of initially constant (i.e. non-accelerated) impurity motion. An oscillatory motion of the impurity atoms has been proposed also in this case, most likely due to a beating between excitonic and polaronic excitations [2]. While our sensitivity to detect this “quantum flutter” effect is marginal, we find that the impurity wave packet upon interacting with the strongly interacting host gas is split into two distinct components, one that is stopped on the timescale of the Fermi time, and another one that is transmitted as if it had not interacted. We are presently not able to interpret this striking observation.
References
[1] F. Meinert et al., Science 356, 945 (2017).
[2] C. M. Mathy et al., Nature Physics 8, 881 (2012).