We study nonequilibrium dephasing in an electronic Mach-Zehnder
interferometer. We demonstrate that the shot noise at the beam splitter of the
interferometer generates an ensemble of nonequilibrium electron density
configurations and that electron interactions induce configuration-specific
phase shifts of an interfering electron. The resulting dephasing exhibits two
characteristic features, a lobe pattern in the visibility and phase jumps of
π, in good agreement with experimental data.Comment: 4 pages, 3 figures; some typos are corrected; published versio