Charge sensitivity of the Inductive Single-Electron Transistor

TL;DR

This paper analyzes the charge sensitivity of an inductive single-electron transistor, showing it can reach very high sensitivity levels limited by quantum noise, with practical experimental results demonstrating a sensitivity of 3×10⁻⁵ e/√Hz.

Contribution

It provides a theoretical model for the charge sensitivity of the device and compares it with experimental data, highlighting the potential for improved detection performance.

Findings

Charge sensitivity can surpass 10⁻⁶ e/√Hz with high Q-factor or SQUID amplifier.

Experimental charge sensitivity achieved is 3×10⁻⁵ e/√Hz.

Bandwidth of the device reaches 100 MHz.

Abstract

We calculate the charge sensitivity of a recently demonstrated device where the Josephson inductance of a single Cooper-pair transistor is measured. We find that the intrinsic limit to detector performance is set by oscillator quantum noise. Sensitivity better than $10^{-6}$e$/\sqrt{\mathrm{Hz}}$ is possible with a high $Q$-value $\sim 10^3$, or using a SQUID amplifier. The model is compared to experiment, where charge sensitivity $3 \times 10^{-5}$e$/\sqrt{\mathrm{Hz}}$ and bandwidth 100 MHz are achieved.