Harvard University Department of Physics

The Gabrielse research group enjoys a variety of atomic, optical, elementary particle, plasma and low temperature physics experiments. A one-electron quantum cyclotron has made it possible to measure the dimensionless electron magnetic moment 15 times more accurately than a measurement that stood for twenty years, and to determine the fine structure constant 20 times more accurately than does any independent method. A separate measurement, in collaboration with Prof. Doyle and Prof. DeMille (Yale), seeks a substantial improvement in measuring the electric dipole moment of the electron.  In addition, the most precise laser spectroscopy of helium fine structure intervals, stabilized by an iodine optical clock and an optical comb, provides a way to test two-electron QED.

Professor Gabrielse led the international TRAP team that developed the techniques to accumulate antiprotons at energies more than 10¹⁰ times lower than previously realized. This enabled the most stringent CPT test with baryons, made by comparing charge-to-mass ratios for a single antiproton and proton to an accuracy of 90 parts per trillion. The international ATRAP Collaboration, also led by Gabrielse, now uses these antiprotons to produce cold antihydrogen atoms, an important step towards comparing antihydrogen and hydrogen atoms via precise laser spectroscopy. Technological spin-offs include a patented solenoid design being used for nuclear magnetic resonance (NMR), magnetic resonance imaging (MRI) and ion cyclotron resonance (ICR), along with improved cell designs for ICR.