Fast charge sensing of a cavity-coupled double quantum dot using a Josephson parametric amplifier

TL;DR

This paper demonstrates a rapid and highly sensitive charge sensing method for a double quantum dot coupled to a superconducting resonator, utilizing a Josephson parametric amplifier to enable real-time quantum dot tuning.

Contribution

The work introduces a novel application of parametric amplification in quantum dot charge sensing, achieving unprecedented speed and sensitivity for real-time quantum device control.

Findings

2000-fold improvement in SNR with parametric amplification

Achieved charge sensitivity of 8 x 10^{-5} e/root(Hz)

Charge stability diagrams obtained in 20 ms for live tuning

Abstract

We demonstrate fast readout of a double quantum dot (DQD) that is coupled to a superconducting resonator. Utilizing parametric amplification in a nonlinear operational mode, we improve the signal-to-noise ratio (SNR) by a factor of 2000 compared to the situation with the parametric amplifier turned off. With an integration time of 400 ns we achieve a SNR of 76. By studying SNR as a function of the integration time we extract an equivalent charge sensitivity of 8 x 10^{-5} e/root(Hz). The high SNR allows us to acquire a DQD charge stability diagram in just 20 ms. At such a high data rate, it is possible to acquire charge stability diagrams in a live "video-mode," enabling real time tuning of the DQD confinement potential.