3,018 research outputs found
Quantum computers can search rapidly by using almost any selective transformations
The search problem is to find a state satisfying certain properties out of a
given set. Grover's algorithm drives a quantum computer from a prepared initial
state to the target state and solves the problem quadratically faster than a
classical computer. The algorithm uses selective transformations to distinguish
the initial state and target state from other states. It does not succeed
unless the selective transformations are very close to phase-inversions. Here
we show a way to go beyond this limitation. An important application lies in
quantum error-correction, where the errors can cause the selective
transformations to deviate from phase-inversions. The algorithms presented here
are robust to errors as long as the errors are reproducible and reversible.
This particular class of systematic errors arise often from imperfections in
apparatus setup. Hence our algorithms offer a significant flexibility in the
physical implementation of quantum search.Comment: 8 pages, Accepted for publication in PR
Application of ERTS-1 Imagery to Flood Inundation Mapping
Application of ERTS-1 imagery to flood inundation mapping in East and West Nishnabotna basins of southwestern Iow
Evaluation of macrophyte control in 38 Florida lakes using triploid grass carp
Florida’s large number of shallow lakes, warm climate and
long growing season have contributed to the development of
excessive growths of aquatic macrophytes that have seriously
interfered with many water use activities. The introduction
of exotic aquatic macrophyte species such as hydrilla (
Hydrilla
verticillata
) have added significantly to aquatic plant problems
in Florida lakes. The use of grass carp (
Ctenopharyngodon
idella
) can be an effective and economical control for aquatic
vegetation such as hydrilla. Early stocking rates (24 to 74
grass carp per hectare of lake area) resulted in grass carp
consumption rates that vastly exceeded the growth rates of
the aquatic plants and often resulted in the total loss of all
submersed vegetation. This study looked at 38 Florida lakes
that had been stocked with grass carp for 3 to 10 years with
stocking rates ranging from < 1 to 59 grass carp per hectare
of lake and 1 to 207 grass carp per hectare of vegetation to
determine the long term effects of grass carp on aquatic macrophyte
communities. The median PAC (percent area coverage)
value of aquatic macrophytes for the study lakes after
they were stocked with grass carp was 14% and the median
PVI (percent volume infested) value of aquatic macrophytes
was 2%. Only lakes stocked with less than 25 to 30 fish per
hectare of vegetation tended to have higher than median
PAC and PVI values. When grass carp are stocked at levels of
> 25 to 30 fish per hectare of vegetation the complete control
of aquatic vegetation can be achieved, with the exception of
a few species of plants that grass carp have extreme difficulty
consuming. If the management goal for a lake is to control
some of the problem aquatic plants while maintaining a
small population of predominately unpalatable aquatic
plants, grass carp can be stocked at approximately 25 to 30
fish per hectare of vegetation
Many-Body Dynamics and Exciton Formation Studied by Time-Resolved Photoluminescence
The dynamics of exciton and electron-hole plasma populations is studied via
time-resolved photoluminescence after nonresonant excitation. By comparing the
peak emission at the exciton resonance with the emission of the continuum, it
is possible to experimentally identify regimes where the emission originates
predominantly from exciton and/or plasma populations. The results are supported
by a microscopic theory which allows one to extract the fraction of bright
excitons as a function of time.Comment: 11 pages, 5 figure
Photoluminescence and Terahertz Emission from Femtosecond Laser-Induced Plasma Channels
Luminescence as a mechanism for terahertz emission from femtosecond
laser-induced plasmas is studied. By using a fully microscopic theory, Coulomb
scattering between electrons and ions is shown to lead to luminescence even for
a spatially homogeneous plasma. The spectral features introduced by the rod
geometry of laser-induced plasma channels in air are discussed on the basis of
a generalized mode-function analysis.Comment: 4 pages with 2 figures
ARCHI: pipeline for light curve extraction of CHEOPS background star
High precision time series photometry from space is being used for a number
of scientific cases. In this context, the recently launched CHEOPS (ESA)
mission promises to bring 20 ppm precision over an exposure time of 6 hours,
when targeting nearby bright stars, having in mind the detailed
characterization of exoplanetary systems through transit measurements. However,
the official CHEOPS (ESA) mission pipeline only provides photometry for the
main target (the central star in the field). In order to explore the potential
of CHEOPS photometry for all stars in the field, in this paper we present
archi, an additional open-source pipeline module{\dag}to analyse the background
stars present in the image. As archi uses the official Data Reduction Pipeline
data as input, it is not meant to be used as independent tool to process raw
CHEOPS data but, instead, to be used as an add-on to the official pipeline. We
test archi using CHEOPS simulated images, and show that photometry of
background stars in CHEOPS images is only slightly degraded (by a factor of 2
to 3) with respect to the main target. This opens a potential for the use of
CHEOPS to produce photometric time series of several close-by targets at once,
as well as to use different stars in the image to calibrate systematic errors.
We also show one clear scientific application where the study of the companion
light curve can be important for the understanding of the contamination on the
main target.Comment: 14 pages, 13 figures, accepted for publication in MNRAS, all code
available at https://github.com/Kamuish/arch
The Precise Formula in a Sine Function Form of the norm of the Amplitude and the Necessary and Sufficient Phase Condition for Any Quantum Algorithm with Arbitrary Phase Rotations
In this paper we derived the precise formula in a sine function form of the
norm of the amplitude in the desired state, and by means of he precise formula
we presented the necessary and sufficient phase condition for any quantum
algorithm with arbitrary phase rotations. We also showed that the phase
condition: identical rotation angles, is a sufficient but not a necessary phase
condition.Comment: 16 pages. Modified some English sentences and some proofs. Removed a
table. Corrected the formula for kol on page 10. No figure
Nuclear Shadowing and the Optics of Hadronic Fluctuations
A coordinate space description of shadowing in deep-inelastic lepton-nucleus
scattering is presented. The picture in the laboratory frame is that of
quark-gluon fluctuations of the high-energy virtual photon, propagating
coherently over large light-cone distances in the nuclear medium. We discuss
the detailed dependence of the coherence effects on the invariant mass of the
fluctuation. We comment on the issue of possible saturation in the shadowing
effects at very small Bjorken-.Comment: 11 pages, 5 figure
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