title: Critical velocity of a mobile impurity in one-dimensional quantum liquids.
abstract: We study the notion of superfluid critical velocity in one spatial dimension. It is shown that, for heavy impurities with mass M exceeding a critical mass Mc, the dispersion develops periodic metastable branches resulting in dramatic changes of dynamics in the presence of an external driving force. In contrast to smooth Bloch oscillations for M<Mc, a heavy impurity climbs metastable branches until it reaches a branch termination point or undergoes a random tunneling event, both leading to an abrupt change in velocity and an energy loss. This is predicted to lead to a nonanalytic dependence of the impurity drift velocity on small forces.
authors.affiliation: School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: M
authors.initials: M
authors.lastname: Schecter
authors.forename: A
authors.initials: A
authors.lastname: Kamenev
authors.forename: D M
authors.initials: DM
authors.lastname: Gangardt
authors.forename: A
authors.initials: A
authors.lastname: Lamacraft