Direct Measurement of the Destruction of Charge Quantization in a Single Electron Box

TL;DR

This study directly measures how charge quantization in a single electron box diminishes as conductance increases, confirming theoretical predictions and demonstrating the electrometer's high sensitivity across the full conductance range.

Contribution

First direct measurement of charge quantization destruction in a single electron box over the entire conductance range using a highly sensitive SET electrometer.

Findings

Charge quantization disappears at G = G_q

Electrometer sensitivity dq ~ 6 x 10^-5 e/√Hz

Quantization destruction aligns with theoretical predictions

Abstract

We report here direct measurements of the destruction of charge quantization in a single electron box, the first over the full range of box-to-lead conductance values from G ~ 0 to the conductance quantum G_q = 2e^2/h, using a sensitive single-electron transistor (SET) electrometer. The sensitivity of the electrometer is measured to be dq ~ 6 x 10^-5 e/sqrt{Hz} and its superiority to conductance measurements of charge fluctuations is clearly demonstrated. As the rate of quantum mechanical tunneling from the box to its lead is increased, the quantization of charge is destroyed, disappearing entirely at G = G_q in agreement with theory.