Thermal Enhancement of Interference Effects in Quantum Point Contacts

TL;DR

This paper investigates how temperature influences interference fringes in a quantum point contact electron interferometer, revealing an unusual enhancement of fringes with increasing temperature that persist beyond expected thermal limits.

Contribution

It introduces a simplified model explaining the temperature-induced enhancement of interference fringes, a phenomenon not previously understood.

Findings

Fringes are spaced by half the Fermi wavelength.

Fringes are enhanced as temperature increases.

Fringes can persist beyond the thermal length.

Abstract

We study an electron interferometer formed with a quantum point contact and a scanning probe tip in a two-dimensional electron gas. The images giving the conductance as a function of the tip position exhibit fringes spaced by half the Fermi wavelength. For a contact opened at the edges of a quantized conductance plateau, the fringes are enhanced as the temperature T increases and can persist beyond the thermal length l_T. This unusual effect is explained assuming a simplified model: The fringes are mainly given by a contribution which vanishes when T -> 0 and has a decay characterized by a T-independent scale.