Atomic, Molecular and Optical Physics

Electrons in Quantum Circuits

Professor Jose Verdu Galiana

Our research plans focus on a single electron in a Penning trap, a system known as a geonium atom, as coined by its inventor the 1989 Nobel Prize winner Hans Dehmelt. The role of the nucleus is played by the adjustable external trapping fields: the electron is bound to an apparatus anchored to the earth (therefore the name geonium). The properties of the geonium atom can be calculated with extremely high precision and it is an outstanding system for testing the laws of physics with very high accuracy.

Penning traps cover a very broad range of applications in Physics. One of the most celebrated results is the measurement of the magnetic dipole moment of the free electron, with an absolute precision of 10-12. For that measurement Dehmelt was awarded the Nobel Prize in Physics.

Recently, the accuracy of that fundamental constant has been improved to 10-13 at the University of Harvard. This represents one of the most precise experimental tests of quantum electrodynamics (QED) up to date. A similar measurement of the g-factor of the positron has allowed for the most accurate test of CPT-invariance in the lepton sector. Moreover, Penning traps are used for determining the masses of elementary particles, such as the electron and the (anti)proton, with relative precisions in the order of 10-10.

They are essential for some tests of the unitarity of the Cabibbo-Kobayashi-Maskawa quark mixing matrix, for obtaining an upper experimental bound to the neutrino mass and also for the production of neutral antihydrogen. Summarizing, Penning traps provide the means for performing very precise tests of nuclear models, the weak interaction, QED and the Standard Model.