Fermi-Edge Resonance and Tunneling in Nonequilibrium Electron Gas

TL;DR

This paper investigates how Fermi-edge singularities behave in nonequilibrium electron gases, revealing complex splitting and broadening effects that depend on the energy distribution, using an exact determinant method.

Contribution

It provides an exact solution for Fermi-edge singularities in nonequilibrium systems with arbitrary energy distributions, overcoming limitations of bosonization.

Findings

Fermi-edge singularity splits into multiple components in nonequilibrium.

Tunneling density of states shows broadened peaks at Fermi sub-levels.

Power law singularities are present in the open loop Green's function.

Abstract

Fermi-edge singularity changes in a dramatic way in a nonequilibrium system, acquiring features which reflect the structure of energy distribution. In particular, it splits into several components if the energy distribution exhibits multiple steps. While conventional approaches, such as bosonization, fail to describe the nonequilibrium problem, an exact solution for a generic energy distribution can be obtained with the help of the method of functional determinants. In the case of a split Fermi distribution, while the `open loop' contribution to Green's function has power law singularities, the tunneling density of states profile exhibits broadened peaks centered at Fermi sub-levels.