81 research outputs found
Spectroscopy on a single trapped 137Ba+ ion for nuclear magnetic octupole moment determination
We present precision measurements of the hyperfine intervals in the 5D3/2
manifold of a single trapped Barium ion, 137 Ba+ . Measurements of the
hyperfine intervals are made between mF = 0 sublevels over a range of magnetic
fields allowing us to interpolate to the zero field values with an accuracy
below a few Hz, an improvement on previous measurements by three orders of
magnitude. Our results, in conjunction with theoretical calculations, provide a
30-fold reduction in the uncertainty of the magnetic dipole (A) and electric
quadrupole (B) hyperfine constants. In addition, we obtain the magnetic
octupole constant (C) with an accuracy below 0.1 Hz. This gives a subsequent
determination of the nuclear magnetic octupole moment, {\Omega}, with an
uncertainty of 1% limited almost completely by the accuracy of theoretical
calculations. This constitutes the first observation of the octupole moment in
137 Ba+ and the most accurately determined octupole moment to date.Comment: 4 pages, 3 figure
Individual addressing and state readout of trapped ions utilizing rf- micromotion
A new scheme for the individual addressing of ions in a trap is described
that does not rely on light beams tightly focused onto only one ion. The scheme
utilizes ion micromotion that may be induced in a linear trap by dc offset
potentials. Thus coupling an individual ion to the globally applied light
fields corresponds to a mere switching of voltages on a suitable set of
compensation electrodes. The proposed scheme is especially suitable for
miniaturized rf (Paul) traps with typical dimensions of about 20-40 microns.Comment: 3 pages, 5 figure
Quantum control of Sr in a miniature linear Paul trap
We report on the construction and characterization of an apparatus for
quantum information experiments using Sr ions. A miniature linear
radio-frequency (rf) Paul trap was designed and built. Trap frequencies above 1
MHz in all directions are obtained with 50 V on the trap end-caps and less than
1 W of rf power. We encode a quantum bit (qubit) in the two spin states of the
electronic ground-state of the ion. We constructed all the necessary
laser sources for laser cooling and full coherent manipulation of the ions'
external and internal states. Oscillating magnetic fields are used for coherent
spin rotations. High-fidelity readout as well as a coherence time of 2.5 ms are
demonstrated. Following resolved sideband cooling the average axial vibrational
quanta of a single trapped ion is and a heating rate of
ms is measured.Comment: 8 pages,9 figure
Quantum state manipulation of trapped atomic ions
A single laser-cooled and trapped 9Be+ ion is used to investigate methods of
coherent quantum-state synthesis and quantum logic. We create and characterize
nonclassical states of motion including "Schroedinger-cat" states. A
fundamental quantum logic gate is realized which uses two states of the
quantized ion motion and two ion internal states as qubits. We explore some of
the applications for, and problems in realizing, quantum computation based on
multiple trapped ions.Comment: Postscript only. 21 pages text, 5 figures., Proc. Workshop on Quantum
Computing, Santa Barbara, CA, Dec. 1996, Submitted to Proc. Roy. Soc.
Observation of power-law scaling for phase transitions in linear trapped ion crystals
We report an experimental confirmation of the power-law relationship between
the critical anisotropy parameter and ion number for the linear-to-zigzag phase
transition in an ionic crystal. Our experiment uses laser cooled calcium ions
confined in a linear radio-frequency trap. Measurements for up to 10 ions are
in good agreement with theoretical and numeric predictions. Implications on an
upper limit to the size of data registers in ion trap quantum computers are
discussed.Comment: Physical Review Letters in press, 4 pages, 4 figure
Dispersion-theoretical analysis of the nucleon electromagnetic form factors: Inclusion of time-like data
We update a recent dispersion--theoretical fit to the nucleon electromagnetic
form factors by including the existing data in the time--like region. We show
that while the time--like data for the proton can be described consistently
with the existing world space--like data, this is not the case for the neutron.
Another measurement of the process is called for. We
furthermore sharpen the previous estimate of the separation between the
perturbative and the non--perturbative regime, which is characterized by a
scale parameter GeV.Comment: 7 pp, LaTeX, uses epsf, 2 figures in separate file, four data points
changed, slight changes in the fits, conclusions unchange
Destabilization of dark states and optical spectroscopy in Zeeman-degenerate atomic systems
We present a general discussion of the techniques of destabilizing dark
states in laser-driven atoms with either a magnetic field or modulated laser
polarization. We show that the photon scattering rate is maximized at a
particular evolution rate of the dark state. We also find that the atomic
resonance curve is significantly broadened when the evolution rate is far from
this optimum value. These results are illustrated with detailed examples of
destabilizing dark states in some commonly-trapped ions and supported by
insights derived from numerical calculations and simple theoretical models.Comment: 14 pages, 10 figure
Accurate spectroscopy of Sr atoms
We report the frequency measurement with an accuracy in the 100 kHz range of
several optical transitions of atomic Sr : at 689 nm, at 688 nm and at 679 nm. Measurements are performed with
a frequency chain based on a femtosecond laser referenced to primary frequency
standards. They allowed the indirect determination with a 70 kHz uncertainty of
the frequency of the doubly forbidden 5s^2^1S_0- 5s5p^3P_0 transition of
Sr at 698 nm and in a second step its direct observation. Frequency
measurements are performed for Sr and Sr, allowing the
determination of , and isotope shifts, as well as the
hyperfine constants.Comment: 12 pages, 16 figure
- …