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Updated: Mar 9, 2026
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Scanning-probe Single-electron Capacitance Spectroscopy
Published on: July 30, 2013
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Measuring the Electron's Charge and the Fine-Structure Constant by Counting Electrons on a Capacitor
E R Williams1, Ruby N Ghosh1, John M Martinis2
1National Institute of Standards and Technology, Gaithersburg, MD 20899.
Summary
Precisely measuring electron charge determines fundamental constants. Advances in single electron tunneling enable precise electron counting and sensitive voltage measurements for this purpose.
Area of Science:
- Quantum physics
- Metrology
Background:
- Electron charge measurement is fundamental to physics.
- Capacitor voltage measurement is a key technique.
Purpose of the Study:
- To determine the electron charge using a capacitor.
- To measure the fine-structure constant.
Main Methods:
- Placing a known number of electrons on a capacitor electrode.
- Measuring the capacitor voltage (Vs).
- Utilizing single electron tunneling (SET) for electron counting and electrometer development.
Main Results:
- Successful determination of electron charge.
- Measurement of the fine-structure constant when using Josephson volt and SI units for capacitance.
Conclusions:
- Single electron tunneling facilitates precise charge measurements.
- This method allows for the determination of fundamental physical constants.
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