1,627 research outputs found
Scalable simultaneous multi-qubit readout with 99.99% single-shot fidelity
We describe single-shot readout of a trapped-ion multi-qubit register using
space and time-resolved camera detection. For a single qubit we measure
0.9(3)x10^{-4} readout error in 400us exposure time, limited by the qubit's
decay lifetime. For a four-qubit register (a "qunybble") we measure an
additional error of only 0.1(1)x10^{-4} per qubit, despite the presence of 4%
optical cross-talk between neighbouring qubits. A study of the cross-talk
indicates that the method would scale with negligible loss of fidelity to
~10000 qubits at a density <~1 qubit/um^2, with a readout time ~1us/qubit.Comment: 4 pages, 3 figures; simulations added to fig.3, with some further
text and figure revisions. Main results unchanged
Manipulation and Detection of a Trapped Yb+ Ion Hyperfine Qubit
We demonstrate the use of trapped ytterbium ions as quantum bits for quantum
information processing. We implement fast, efficient state preparation and
state detection of the first-order magnetic field-insensitive hyperfine levels
of 171Yb+, with a measured coherence time of 2.5 seconds. The high efficiency
and high fidelity of these operations is accomplished through the stabilization
and frequency modulation of relevant laser sources.Comment: 10 pages, 9 figures, 1 tabl
T-junction ion trap array for two-dimensional ion shuttling, storage and manipulation
We demonstrate a two-dimensional 11-zone ion trap array, where individual
laser-cooled atomic ions are stored, separated, shuttled, and swapped. The trap
geometry consists of two linear rf ion trap sections that are joined at a 90
degree angle to form a T-shaped structure. We shuttle a single ion around the
corners of the T-junction and swap the positions of two crystallized ions using
voltage sequences designed to accommodate the nontrivial electrical potential
near the junction. Full two-dimensional control of multiple ions demonstrated
in this system may be crucial for the realization of scalable ion trap quantum
computation and the implementation of quantum networks.Comment: 3 pages, 5 figure
Exploring the Structure of Distant Galaxies with Adaptive Optics on the Keck-II Telescope
We report on the first observation of cosmologically distant field galaxies
with an high order Adaptive Optics (AO) system on an 8-10 meter class
telescope. Two galaxies were observed at 1.6 microns at an angular resolution
as high as 50 milliarcsec using the AO system on the Keck-II telescope. Radial
profiles of both objects are consistent with those of local spiral galaxies and
are decomposed into a classic exponential disk and a central bulge. A
star-forming cluster or companion galaxy as well as a compact core are detected
in one of the galaxies at a redshift of 0.37+/-0.05. We discuss possible
explanations for the core including a small bulge, a nuclear starburst, or an
active nucleus. The same galaxy shows a peak disk surface brightness that is
brighter than local disks of comparable size. These observations demonstrate
the power of AO to reveal details of the morphology of distant faint galaxies
and to explore galaxy evolution.Comment: 5 pages, Latex, 3 figures. Accepted for publication in P.A.S.
Sunspot observations from the SOUP instrument on Spacelab 2
A series of white light images obtained by the SOUP instrument on Spacelab 2 of active region 4682 on August 5, 1985 were analyzed in the area containing sunspots. Although the umbra of the spot is underexposed, the film is well exposed in the penumbral regions. These data were digitally processed to remove noise and to separate p-mode oscillations from low velocity material motions. The results of this preliminary investigation include: (1) proper motion measurements of a radial outflow in the photospheric granulation pattern just outside the penumbra; (2) discovery of occasional bright structures (streakers) that appear to be ejected outward from the penumbra; (3) broad dark clouds moving outward in the penumbra in addition to the well known bright penumbral grains moving inward; (4) apparent extensions and contractions of penumbral filaments over the photosphere; and (5) observation of a faint bubble or loop-like structure which seems to expand from two bright penumbral filaments into the photosphere
Comparison of the Geometrical Characters Inside Quark- and Gluon-jet Produced by Different Flavor Quarks
The characters of the angular distributions of quark jets and gluon jets with
different flavors are carefully studied after introducing the cone angle of
jets. The quark jets and gluon jets are identified from the 3-jet events which
are produced by Monte Carlo simulation Jetset7.4 in e+e- collisions at =91.2GeV. It turns out that the ranges of angular distributions of gluon jets
are obviously wider than that of quark jets at the same energies. The average
cone angles of gluon jets are much larger than that of quark jets. As the
multiplicity or the transverse momentum increases, the cone-angle distribution
without momentum weight of both the quark jet and gluon jet all increases, i.e
the positive linear correlation are present, but the cone-angle distribution
with momentum weight decreases at first, then increases when n > 4 or p_t > 2
GeV. The characters of cone angular distributions of gluon jets produced by
quarks with different flavors are the same, while there are obvious differences
for that of the quark jets with different flavors.Comment: 13 pages, 6 figures, to be published on the International Journal of
Modern Physics
Weak dipole moment of in collisions with longitudinally polarized electrons
It is pointed out that certain CP-odd momentum correlations in the production
and subsequent decay of tau pairs in collisions get enhanced when the
is longitudinally polarized. Analytic expressions for these correlations
are obtained for the single-pion decay mode of when have
a ``weak" dipole form factor (WDFF) coupling to . For collisions
at the peak, a sensitivity of about 1-5\mbox{ cm} for
the WDFF can be reached using a {\em single} decay
channel, with 's likely to be available at the SLC at Stanford with
polarization of 62\%-75\%.Comment: 9 pages, Latex, PRL-TH-93/17 (Revised
Magneto-optical Trapping of Cadmium
We report the laser-cooling and confinement of Cd atoms in a magneto-optical
trap, and characterize the loading process from the background Cd vapor. The
trapping laser drives the 1S0-1P1 transition at 229 nm in this two-electron
atom and also photoionizes atoms directly from the 1P1 state. This
photoionization overwhelms the other loss mechanisms and allows a direct
measurement of the photoionization cross section, which we measure to be
2(1)x10^(-16)cm^(2) from the 1P1 state. When combined with nearby laser-cooled
and trapped Cd^(+) ions, this apparatus could facilitate studies in ultracold
interactions between atoms and ions.Comment: 8 pages, 11 figure
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