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

Understand

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).