Quantum Coherence Beyond the Thermal Length

TL;DR

This paper investigates the persistence of quantum interference fringes in electron flow experiments beyond the thermal and phase coherence lengths, proposing mechanisms for their survival and methods to measure coherence length independently.

Contribution

It introduces a new understanding of quantum coherence beyond traditional length scales and presents a model explaining fringe survival through higher-order scattering effects.

Findings

Interference fringes persist beyond the thermal length in experiments.

Quantum simulations confirm fringe survival with thermal averaging.

Higher-order scattering mechanisms enable coherence beyond phase coherence length.

Abstract

Recent experiments have used scattering to map the flow of electrons in a two-dimensional electron gas. Among other things, the data from these experiments show perseverance of regular interference fringes beyond the kinematic thermal length. These fringes are seen in full quantum-mechanical simulations with thermal averaging, and within the phase coherence length they can also be understood with a simple, single-scattering model. This effect provides a new way to gauge the coherence length independent of thermal broadening. Appealing to higher-order scattering, we present a mechanism by which interference fringes may survive even beyond the phase coherence length.