Design of a Cooper pair box electrometer for application to solid-state and astroparticle physics

TL;DR

This paper presents a novel Cooper pair box electrometer operating at millikelvin temperatures, offering high sensitivity and potential advantages over traditional charge amplifiers for low-back-action applications.

Contribution

The paper introduces a new electrometer design based on a Cooper Pair box coupled to a microwave resonator, with optimized parameters for enhanced charge sensitivity.

Findings

Achieves charge sensitivity of a few 10^{-7} e/√Hz.

Outperforms existing single charge electrometers.

Provides a detailed analysis of device sensitivity dependence.

Abstract

We describe the design and principle of operation of a fast and sensitive electrometer operated at millikelvin temperatures, which aims at replacing conventional semiconducting charge amplifiers in experiments needing low back-action or high sensitivity. The electrometer consists of a Cooper Pair box (CPB) coupled to a microwave resonator, which converts charge variations to resonance frequency shifts. We analyze the dependence of the sensitivity on the various parameters of the device, and derive their optimization. By exploiting the nonlinearities of this electrometer, and using conventional nanofabrication and measurement techniques, a charge sensitivity of a few $10^{- 7} e / \sqrt{Hz}$ can be achieved which outperforms existing single charge electrometers.