490 research outputs found
Cavity Control of a Single-Electron Quantum Cyclotron:\\Measuring the Electron Magnetic Moment
Measurements with a one-electron quantum cyclotron determine the electron
magnetic moment, given by , and the fine structure
constant, . Brief
announcements of these measurements are supplemented here with a more complete
description of the one-electron quantum cyclotron and the new measurement
methods, a discussion of the cavity control of the radiation field, a summary
of the analysis of the measurements, and a fuller discussion of the
uncertainties
Direct Measurement of the Proton Magnetic Moment
The proton magnetic moment in nuclear magnetons is measured to be
, a 2.5 ppm (parts per
million) uncertainty. The direct determination, using a single proton in a
Penning trap, demonstrates the first method that should work as well with an
antiproton as with a proton. This opens the way to measuring the antiproton
magnetic moment (whose uncertainty has essentially not been reduced for 20
years) at least times more precisely
Optimized Planar Penning Traps for Quantum Information Studies
A one-electron qubit would offer a new option for quantum information
science, including the possibility of extremely long coherence times.
One-quantum cyclotron transitions and spin flips have been observed for a
single electron in a cylindrical Penning trap. However, an electron suspended
in a planar Penning trap is a more promising building block for the array of
coupled qubits needed for quantum information studies. The optimized design
configurations identified here promise to make it possible to realize the
elusive goal of one trapped electron in a planar Penning trap for the first
time - a substantial step toward a one-electron qubit
Towards an Improved Test of the Standard Model's Most Precise Prediction
The electron and positron magnetic moments are the most precise prediction of
the standard model of particle physics. The most accurate measurement of a
property of an elementary particle has been made to test this result. A new
experimental method is now being employed in an attempt to improve the
measurement accuracy by an order of magnitude. Positrons from a "student
source" now suffice for the experiment. Progress toward a new measurement is
summarized
Gaseous He Nuclear Magnetic Resonance Probe for Cryogenic Environments
Normal nuclear magnetic resonance (NMR) probes cannot be used to make high
frequency resolution measurements in a cryogenic environment because they lose
their frequency resolution when the liquid sample in the probe freezes. A
gaseous He NMR probe, designed and constructed to work naturally in such
cryogenic environments, is demonstrated at 4.2 K and 5.3 Tesla to have a
frequency resolution better than 0.4 part per billion. As a demonstration of
its usefulness, the cryogenic probe is used to shim a superconducting solenoid
with a cryogenic interior to produce a magnetic field with a high spatial
homogeneity, and to measure the magnetic field stability.Comment: 9 pages, 11 figure
Resolving an Individual One-Proton Spin Flip to Determine a Proton Spin State
Previous measurements with a single trapped proton or antiproton detected
spin resonance from the increased scatter of frequency measurements caused by
many spin flips. Here a measured correlation confirms that individual spin
transitions and states are detected instead. The high fidelity suggests that it
may be possible to use quantum jump spectroscopy to measure the p and \pbar
magnetic moments much more precisely.Comment: 4 pages, 7 figure
Single-Particle Self-Excited Oscillator
Electronic feedback is used to self-excite the axial oscillation of a single electron in a Penning trap. Large, stable, easily detected oscillations arise even in an anharmonic potential. Amplitudes are controlled by adjusting the feedback gain, and frequencies can be made nearly independent of amplitude fluctuations. Quantum jump spectroscopy of a perpendicular cyclotron motion reveals the absolute temperature and amplitude of the self-excited oscillation. The possibility to quickly measure parts per billion frequency shifts could open the way to improved measurements of e-, e+, p, and [overline p] magnetic moments
New Measurement of the Electron Magnetic Moment and the Fine Structure Constant
A measurement using a one-electron quantum cyclotron gives the electron
magnetic moment in Bohr magnetons, g/2 = 1.001 159 652 180 73 (28) [0.28 ppt],
with an uncertainty 2.7 and 15 times smaller than for previous measurements in
2006 and 1987. The electron is used as a magnetometer to allow lineshape
statistics to accumulate, and its spontaneous emission rate determines the
correction for its interaction with a cylindrical trap cavity. The new
measurement and QED theory determine the fine structure constant, with
alpha^{-1} = 137.035 999 084 (51) [0.37 ppb], and an uncertainty 20 times
smaller than for any independent determination of alpha.Comment: 4 pages, 4 figure
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