Measuring the Electron's Charge and the Fine-Structure Constant by Counting Electrons on a Capacitor

E R Williams; Ruby N Ghosh; John M Martinis

doi:10.6028/jres.097.010

Measuring the Electron's Charge and the Fine-Structure Constant by Counting Electrons on a Capacitor

J Res Natl Inst Stand Technol. 1992 Mar-Apr;97(2):299-304. doi: 10.6028/jres.097.010.

Authors

E R Williams¹, Ruby N Ghosh¹, John M Martinis²

Affiliations

¹ National Institute of Standards and Technology, Gaithersburg, MD 20899.
² National Institute of Standards and Technology, Boulder, CO 80303.

Abstract

The charge of the electron can be determined by simply placing a known number of electrons on one electrode of a capacitor and measuring the voltage, V_s, across the capacitor. If V_s is measured in terms of the Josephson volt and the capacitor is measured in SI units then the fine-structure constant is the quantity determined. Recent developments involving single electron tunneling, SET, have shown bow to count the electrons as well as how to make an electrometer with sufficient sensitivity to measure the charge.

Keywords: calculable capacitor; coulomb blockade; electron charge; electron counting; fine-structure constant; single electron tunneling.