New Measurement of the Electron Magnetic Moment and the Fine Structure Constant

TL;DR

This paper reports a highly precise measurement of the electron magnetic moment using a quantum cyclotron, leading to an improved determination of the fine structure constant with unprecedented accuracy.

Contribution

The study introduces a new measurement technique with significantly reduced uncertainty, refining the values of fundamental constants and testing quantum electrodynamics.

Findings

Electron magnetic moment measured with 0.28 ppt uncertainty.

Fine structure constant determined with 0.37 ppb precision.

Measurement accuracy surpasses previous results by factors of 15 and 20.

Abstract

A measurement using a one-electron quantum cyclotron gives the electron magnetic moment in Bohr magnetons, g/2 = 1.001 159 652 180 73 (28) [0.28 ppt], with an uncertainty 2.7 and 15 times smaller than for previous measurements in 2006 and 1987. The electron is used as a magnetometer to allow lineshape statistics to accumulate, and its spontaneous emission rate determines the correction for its interaction with a cylindrical trap cavity. The new measurement and QED theory determine the fine structure constant, with alpha^{-1} = 137.035 999 084 (51) [0.37 ppb], and an uncertainty 20 times smaller than for any independent determination of alpha.