Theory of a double-dot charge detector

TL;DR

This paper analyzes a double quantum dot charge detector using a minimal model, calculating its signal and noise characteristics to identify optimal detection bandwidth through a noise spectrum dip at the double Rabi frequency.

Contribution

It introduces a theoretical framework for understanding the noise and signal in a double-dot charge detector, highlighting the detection bandwidth via spectral analysis.

Findings

Noise spectrum shows a dip at the double Rabi frequency

Bandwidth for charge detection is defined by the noise dip

Model provides insights into detector signal and noise behavior

Abstract

A double quantum dot charge detector, with one dot Coulomb coupled to the electron to be detected and the other modulated by a time-dependent plunger voltage, is analyzed in a minimal model. The signal and noise of the detector are calculated by a standard master equation and MacDonald formula technique. We find a dip in the noise spectrum at the double Rabi frequency of the double dot, defining the bandwidth available for detecting charges in motion.