Counting statistics and detector properties of quantum point contacts

TL;DR

This paper analyzes the quantum detector properties of quantum point contacts (QPCs), showing how electron counting statistics determine their performance and proposing methods to achieve quantum-limited detection by restoring phase information.

Contribution

It provides a comprehensive analysis of QPC detector properties for arbitrary parameters and introduces a way to restore phase information for optimal quantum detection.

Findings

QPC detector properties are governed by electron counting statistics.

Conditions for quantum-limited operation are identified for arbitrary coupling.

Phase information can be restored using an electronic Mach-Zehnder interferometer.

Abstract

Quantum detector properties of the quantum point contact (QPC) are analyzed for arbitrary electron transparency and coupling strength to the measured system and are shown to be determined by the electron counting statistics. Conditions of the quantum-limited operation of the QPC detector which prevent information loss through the scattering time and scattering phases are found for arbitrary coupling. We show that the phase information can be restored and used for the quantum-limited detection by inclusion of the QPC detector in the electronic Mach-Zehnder interferometer.