title: Orthogonality catastrophe and shock waves in a nonequilibrium Fermi gas.
abstract: A semiclassical wave packet propagating in a dissipationless Fermi gas inevitably enters a "gradient catastrophe" regime, where an initially smooth front develops large gradients and undergoes a dramatic shock-wave phenomenon. The nonlinear effects in electronic transport are due to the curvature of the electronic spectrum at the Fermi surface. They can be probed by a sudden switching of a local potential. In equilibrium, this process produces a large number of particle-hole pairs, a phenomenon closely related to the orthogonality catastrophe. We study a generalization of this phenomenon to the nonequilibrium regime and show how the orthogonality catastrophe cures the gradient catastrophe, by providing a dispersive regularization mechanism.
authors.affiliation: James Frank Institute, University of Chicago, 5640 S. Ellis Ave., Chicago, Illinois 60637, USA.
authors.forename: E
authors.initials: E
authors.lastname: Bettelheim
authors.forename: A G
authors.initials: AG
authors.lastname: Abanov
authors.forename: P
authors.initials: P
authors.lastname: Wiegmann