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Professor Gerald Gabrielse
Harvard Physics Department
Now at Center for Fundamental Physics at Low Energy, Northwestern University

Harvard Shield
People Opportunities for Graduate Students and Postdocs Trivia: Angels and Demons
Printable Narrative on Group Research
Trivia: Jim Carey and Conan O'Brien

Recent Advance

Order of Magnitude Improved Measurement of the Electron's Electric Dipole Moment

First Observation of an Individual Spin Transition for an Proton

Trapped Antihydrogen in Its Ground State      (how to Avoid Mirror-Trapped Antiprotons)

680-fold Improved Measurement of the Antiproton Magnetic Moment

First Direct Measurement of the Proton Magnetic Moment

Current Research Projects (department overview)

Lepton Magnetic Moments -- one apparatus, many results (below)

Supported by NSF AMO
most accurate measurements of g/2 and a


T. Myers,
Dr. S. Fayer,
G. Gabrielse,
(many earlier

ATRAP Antihydrogen Studies (summary from Physics Today)

Supported by NSF and AFOSR
Penning-Ioffe trap for antihydrogen
T. Morrison,
D. Zambrano,
G. Gabrielse,
and collaborators

Proton and Antiproton Magnetic Moments

Supported by NSF and AFOSR
Our new measurement is 680 times more precise than all previous measurements
M. Marshall,
K. Marable,
A. Ionescu,
G. Gabrielse,

Investigation of a One-Electron Qubit

planar Penning trap
  • Goal 1: To identify planar the first trap designs within which an electron qubit could be realized (Recent PRA)
  • Goal 2: To observe one electron suspended within a planar trap chip
  • Goal 3: To demonstrate a one-electron qubit for the first time
  • Goal 4: To couple one-electron qubits
  • Goal 5: To investigate a coupled array of one-electron qubits

          PRA: consideration of two entangled electrons

J. Goldman,
G. Gabrielse,

ACME Search for the Electric Dipole Moment of an Electron


  • Use ThO molecule
  • Goal is a significantly improved electron EDM measurement or limit on a 5 year time scale


          PRA: overview and initial progress

C. Panda,
D. Ang,
C. Meisenhelder,
G. Gabrielse,
(and collaborators
from the DeMille
and Doyle groups)

Sample of Completed Projects (overview)

Why Does Sideband Mass Spectroscopy Work?

Supported by NSF, AFOSR and the Humboldt Foundation

What "deeper magic" makes the sideband frequency, ?+ + ?-, be a good approximation to the cyclotron frequency?

G. Gabrielse

Comparing Q/M of the Antiproton and Proton to 9 parts in 1011

Was supported by NSF AMO and AFOSR
improving antiproton q/m by factor of almost a million
  • Most stringent test of CPT invariance with a baryon system
  • Nearly a million times more precise than previous CPT tests with baryons
  • Series of three measurements with increasing accuracy

Methods to Slow, Trap, Electron-Cool, and Accumulate Cold Antiprotons

Was supported by NSF AMO and AFOSR
first antiproton trap
  • Developed by the Gabrielse group and TRAP collaborators
  • Used to get cold antiprotons for Q/M measurements
  • Used by and makes possible all cold antihydrogen experiments


  • First capture of antiprotons in a Penning trap
  • First electron-cooling of trapped antiprotons
  • Stacking antiprotons

  • Brown-Gabrielse Invariance Theorem:


    Makes possible many of the most precise measurements in particle, atomic, and nuclear physics


    • Makes possible the most accurate measurements of magnetic moments
    • Makes possible the most accurate ion mass spectroscopy
    • Makes possible the most accurate nuclear mass spectrometry

    Inventing Designs for Penning Traps

    Was supported by NSF AMO and AFOSR
    cylindrical Penning trap

    Superconducting Solenoid that Shields Magnetic Field Fluctuations

    Was supported by NSF AMO, AFOSR and NIST

    • Cancels by a factor of 250 or more any change in the external magnet field
    • A flux change in the solenoid produces a current, that produces a field, that cancels the field change at the center of the system
    • No active electronics
    • Made it possible to do antiproton Q/M measurements not far from cycling LEAR and PS magnets
    • Allows MRI imaging machines to be located nearer to elevators, etc.
    • Used for stable ICR mass spectrometry (e.g. to analyze pharmaceuticals)

    Theory of One Particle in a Penning Trap

    Was supported by DOE and NSF

    • The often-cited basic review of the properties of a charged particle in a Penning trap 
              (click on cover image to download)

    Last updated January 2013.