Gerald Gabrielse Leverett Professor of Physics, Harvard University. New Measurement of the Electron Magnetic Moment and the Fine Structure Constant

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1 Gerald Gabrielse Leverett Professor of Physics, Harvard University New Measurement of the Electron Magnetic Moment and the Fine Structure Constant Remarkably, the famous UW measurement of the electron magnetic moment has stood since With QED theory, this measurement has determined the accepted value of the fine structure constant. This colloquium is about a new Harvard measurement of these fundamental constants. The new measurement has an uncertainty that is about six times smaller, and it shifts the values by 1.7 standard deviations. The more accurate value of the electron magnetic moment, together with QED theory, determines the fine structure constant about 10 times more accurately than any rival method. One electron suspended in a Penning trap is used for the new measurement, like in the old measurement. What is different is that the lowest quantum levels of the spin and cyclotron motion are resolved, and the cyclotron as well as spin frequencies are determined using quantum jump spectroscopy. In addition, a 0.1 K Penning trap that is also a cylindrical microwave cavity is used to control the radiation field, to suppress spontaneous emission by more than a factor of 100, to control cavity shifts, and to eliminate the blackbody photons that otherwise stimulate excitations from the cyclotron ground state. Finally, great signal-to-noise for one-quantum transitions is obtained using electronic feedback to realize the first one-particle self-excited oscillator. The new methods may also allow a million times improved measurement of the 500 times smaller antiproton magnetic moment. New Measurement of the Electron Magnetic Moment B. Odom, D. Hanneke, B. D Urson and G. Gabrielse, Phys. Rev. Lett. 97, (2006). New Determination of the Fine Structure Constant G. Gabrielse, D. Hanneke, T. Kinoshita, M. Nio, B. Odom, Phys. Rev. Lett. 97, (2006). AIP Physics Story of the Year (Phys. News Update, 5 Dec. 2006) Science 313, (2006) Nature 442, (2006) Physics Today, (August, 2006) Cern Courier (October 2006) New Scientist 2568, (2006) Physics World (March 2007) Publications related to this work can be downloaded from:

2 Gerald Gabrielse Gerald Gabrielse, Leverett Professor of Physics at Harvard University, leads and enjoys a variety of atomic, optical, elementary particle, plasma and low temperature physics experiments. Very recently he and his students made the most accurate measurements of the electron magnetic moment and the fine structure constant. He leads the international ATRAP Collaboration (at CERN in Geneva, Switzerland) that made cold antihydrogen atoms with a view to probing these antimatter atoms with accurate laser spectroscopy. The Tom Stoppard play Hapgood and the current best seller Angels and Demons are fictionalizations of his antiproton work. He is the author of more than 130 scientific publications, and gives numerous outside university colloquia and invited talks at scientific conferences nearly 40 in He chaired the Harvard Physics Department from He has served on the executive committees of both the American Physical Society s (APS) Division of Atomic, Molecular and Optical Physics and the APS Topical Group on Precision Measurement. In 2000, he was awarded the Levenson Teaching Award for a senior faculty member at Harvard for his "Reality Physics" course for non-science students. He was awarded the 2002 Davisson-Germer Prize by the American Physical Society "for pioneering work in trapping, cooling, and precision measurements of the properties of matter and antimatter in ion traps. Harvard awarded him the George Ledlie Prize in 2004, a prize awarded every two years to someone who "since the last awarding of said prize has by research, discovery or otherwise made the most valuable contribution to science, or in any way for the benefit of mankind." Professor Gabrielse received Germany s Alexander von Humboldt Research Award in Professor Gabrielse taught and served as the Scientist in Residence at Lexington Christian High School, and he served on the board of trustees of the North Shore Christian grade school. He served six years on the board of trustees of Calvin College, and chaired its education committee. He is currently a member of the board of trustees of Trinity Christian College, and also serves on the Northeast Regional Council of Calvin College. A resume is available at

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