Dynamics and Bloch oscillations of mobile impurities in one-dimensional quantum liquids

We study the dynamics of a mobile impurity moving in a one-dimensional quantum liquid. Such an impurity induces a strong, non-linear depletion of the liquid around it. The dispersion relation of the combined object, called depleton, is a periodic function of its momentum with the period 2 pi n, where n is the mean density of the liquid. In the adiabatic approximation, a constant external force acting on the impurity leads to the Bloch oscillations of the impurity around a fixed position. Dynamically, such oscillations are accompanied by the radiation of energy in the form of phonons. The ensuing energy loss results in the uniform drift of the oscillation center. We derive exact results for the radiation-induced mobility as well as the thermal friction force in terms of the equilibrium dispersion relation of the dressed impurity (depleton). These results show that there is a wide range of external forces where the (drifted) Bloch oscillations exist and may be observed experimentally. (C) 2011 Elsevier Inc. All rights reserved.