GABRIELSE RESEARCH GROUP

Professor Gerald Gabrielse
Harvard Physics Department

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

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

• Positrons trapped in new apparatus on the road to improved CPT test (2012)
• Most accurate measurement of the electron magnetic moment
  
is the most precise measurement of the property of an elementary particle     

• (AIP Physics story of the year, etc.)
• Most accurate determination of the fine structure constant
• Most stringent test of quantum electrodynamics theory
• Limit on electron substructure
• Most stringent test of CPT invariance with leptons

ATRAP Antihydrogen Studies (summary from Physics Today)

• Trapped antihydrogen in its ground state without mirror-trapped antiprotons
  
• Studies of centrifugal separation in antiproton-electron plasmas and adiabatic cooling of antiprotons
• First antihydrogen production within a Penning-Ioffe trap
• Antiproton confinement within a Penning-Ioffe trap
• Laser-controlled antihydrogen production (second method to make antihydrogen)
• Antihydrogen velocity and an interpretation
• Our first observation of slow antihydrogen atoms
(followed immediately by an improved method)
      Slow antihydrogen observations are the AIP Physics Story of the Year
• First positron cooling of antiprotons (first method for making antihydrogen)
• Nested Penning Trap (proposed, first demonstration with protons and electrons,
  first filling with positrons and electrons)
• All slow antihydrogen experiments use our accumulation methods

Proton and Antiproton Magnetic Moments

• Goal: 10,000,000 times improved comparison of the antiproton and proton (goal stated).
  
• First realization of a one-proton self-excited oscillator should allow more sensitive detection of proton and antiproton spin flips.
  
• First one-particle measurement of the proton magnetic moment. The 2.5 ppm precision demonstrates a method for measuring the antiproton magnetic moment.
• First one-particle measurement of the antiproton magnetic moment is done by our ATRAP Collaboration.  The 4.4 ppm precision is 680 times better than realized in previous measurements.
  
• Correlation function confirms the first observation of an individual one-proton spin flip.
  Shows possibility of quantum jump spectroscopy to measure the antiproton magnetic moment 1000 to 10000 more precisely.
  

Investigation of a One-Electron Qubit

• 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

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

Why Does Sideband Mass Spectroscopy Work?

• PRL
• longer report

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

• 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

• 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

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

• derivation
• review of its use
• foundation for accurate nuclear mass measurements

Inventing Designs for Penning Traps

• Orthogonalized hyperbolic Penning traps (overview, design, damping)
• Cylindrical Penning traps (overview, design, demonstration with one electron)
• Open-access cylindrical traps (overview, design)
• Planar Penning traps (overview)

Superconducting Solenoid that Shields Magnetic Field Fluctuations

• 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)

• design
• patent
• demonstration

Theory of One Particle in a Penning Trap

• The often-cited basic review of the properties of a charged particle in a Penning trap