# Electron counting capacitance standard and quantum metrology triangle experiments at PTB

## TL;DR

This paper reports on the final results and challenges of the electron counting capacitance standard experiment at PTB, highlighting systematic uncertainties, capacitor issues, and implications for future quantum metrology triangle experiments.

## Contribution

It provides a comprehensive analysis of the PTB experiment's uncertainties, discusses capacitor-related problems, and offers insights for future quantum metrology triangle research.

## Key findings

- Systematic uncertainties were experimentally quantified.
- Capacitor-related issues limited measurement accuracy.
- Future experiments require improved capacitor technology and small-current metrology.

## Abstract

This paper summarizes the final results of the electron counting capacitance standard experiment at the Physikalisch-Technische Bundesanstalt (PTB) achieved since the publication of a preliminary result in 2012. All systematic uncertainty contributions were experimentally quantified and are discussed. Frequency-dependent measurements on the 1 pF cryogenic capacitor were performed using a high-precision transformer-based capacitance bridge with a relative uncertainty of 0.03 microF/F. The results revealed a crucial problem related to the capacitor, which hampered realizing the quantum metrology triangle with an accuracy corresponding to a combined total uncertainty of better than a few parts per million and eventually caused the discontinuation of the experiment at PTB. This paper provides a conclusion on the implications for future quantum metrology triangle experiments from the latest CODATA adjustment of fundamental constants, and summarizes perspectives and outlooks on future quantum metrology triangle experiments based on topical developments in small-current metrology.

---
Source: https://tomesphere.com/paper/1701.04759