Mode specific backscattering in a quantum point contact

TL;DR

This paper introduces a scanning gate grid measurement technique to analyze mode-specific backscattering in a quantum point contact, revealing interference effects and mode structures with high spatial resolution.

Contribution

The study presents a novel measurement method that enables detailed spatial analysis of conductance modes and interference phenomena in quantum point contacts.

Findings

Interference fringes coexist with distorted QPC conductance plateaus.

The mode structure of each plateau can be spatially resolved.

Capacitive coupling effects are effectively compensated.

Abstract

We demonstrate a scanning gate grid measurement technique consisting in measuring the conductance of a quantum point contact (QPC) as a function of gate voltage at each tip position. Unlike conventional scanning gate experiments, it allows investigating QPC conductance plateaus affected by the tip at these positions. We compensate the capacitive coupling of the tip to the QPC and discover that interference fringes coexist with distorted QPC plateaus. We spatially resolve the mode structure for each plateau.