Fast sensing of double-dot charge arrangement and spin state with an rf sensor quantum dot

TL;DR

This paper demonstrates a rapid, highly sensitive rf sensor quantum dot for single-shot detection of charge and spin states in double quantum dots, significantly outperforming traditional sensors in speed and sensitivity.

Contribution

Introduces a novel rf sensing technique using a sensor quantum dot that enhances sensitivity and speed in detecting charge and spin states compared to existing methods.

Findings

Measurement times as short as 100 ns

Sensor quantum dot is 30 times more sensitive than quantum point contact sensors

Achieves three times greater signal-to-noise ratio in rf measurements

Abstract

Single-shot measurement of the charge arrangement and spin state of a double quantum dot are reported, with measurement times down to ~ 100 ns. Sensing uses radio-frequency reflectometry of a proximal quantum dot in the Coulomb blockade regime. The sensor quantum dot is up to 30 times more sensitive than a comparable quantum point contact sensor, and yields three times greater signal to noise in rf single-shot measurements. Numerical modeling is qualitatively consistent with experiment and shows that the improved sensitivity of the sensor quantum dot results from reduced screening and lifetime broadening.