Colloquium: Determination of the fine structure constant using atom interferometry and test of quantum electrodynamics

02/07/2013

16:00

M1.43, W&N-building, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam

Colloquium: Determination of the fine structure constant using atom interferometry and test of quantum electrodynamics

Dr. Pierre Clade, Ecole Normale Superieure, Paris, France

Wm Vassen

LaserLaB

Sciences

Seminar

Abstract

Quantum Electrodynamics (QED) was formalized about 60 years ago to explain two phenomena : the Lamb shifts in atomic hydrogen and the anomalous magnetic moment of the electron. Nowadays, these two phenomena are still used to precisely test the QED. In order to do such a test, especially the test based on the measurement of the magnetic moment of the electron, we need a precise determination of the fine structure constant alpha, which is the constant that characterize the strength of the electromagnetic interactions.

In this talk, I will present the determination of alpha that we have made at the Laboratoire Kastler Brossel. This determination is deduced from a measurement of the recoil velocity of an atom that absorbs a photon using an atom interferometer. The value of alpha that we have obtained, 1/137.035999037(91), has an uncertainty of 6.6x10^{-10}. The value agrees with the experimental value obtained using the anomalous magnetic moment of the electron, making an unprecedented test of the QED. Moreover, the precision is large enough to verify for the first time the muonic and hadronic contributions to this anomaly.


Dr. Pierre Clade