Abstract: Measurements of the fine structure constant α are powerful tests of the overall consistency of theory and experiment across physics. We have measured α at 0.2 part-per-billion (ppb) accuracy, via cesium-133 atoms in a matter-wave interferometer. We used multiphoton interactions to reduce the statistical uncertainty and enabled control of systematic effects. This is an unprecedented test of the standard model of particle physics, being the first direct measurement of α with an error below the 5th order quantum electrodynamics contribution in the electron's gyromagnetic anomaly. It also has implications for the unexplained anomaly of the muon's magnetic moment, and strongly constrains multiple dark sector candidates as well as substructure of the electron.
Biography: “Holger Müller successfully applied for his first patent when he was 14. Later, he did his undergraduate thesis with Jürgen Mlynek at the University of Konstanz, Germany. He graduated from Humboldt-University, Berlin, with Achim Peters as advisor. Müller received a fellowship of the Alexander von Humboldt foundation and joined the group of Steven Chu in Stanford as a postdoc. In July 2008, he joined the physics faculty at U.C. Berkeley.”