1,527 research outputs found
Use of LANDSAT data for automatic classification and area estimation of sugarcane plantation in Sao Paulo state, Brazil
Ten segments of the size 20 x 10 km were aerially photographed and used as training areas for automatic classifications. The study areas was covered by four LANDSAT paths: 235, 236, 237, and 238. The percentages of overall correct classification for these paths range from 79.56 percent for path 238 to 95.59 percent for path 237
Optimal tracking for pairs of qubit states
In classical control theory, tracking refers to the ability to perform
measurements and feedback on a classical system in order to enforce some
desired dynamics. In this paper we investigate a simple version of quantum
tracking, namely, we look at how to optimally transform the state of a single
qubit into a given target state, when the system can be prepared in two
different ways, and the target state depends on the choice of preparation. We
propose a tracking strategy that is proved to be optimal for any input and
target states. Applications in the context of state discrimination, state
purification, state stabilization and state-dependent quantum cloning are
presented, where existing optimality results are recovered and extended.Comment: 15 pages, 8 figures. Extensive revision of text, optimality results
extended, other physical applications include
Entanglement universality of two-qubit X-states
We demonstrate that for every two-qubit state there is a X-counterpart, i.e.,
a corresponding two-qubit X-state of same spectrum and entanglement, as
measured by concurrence, negativity or relative entropy of entanglement. By
parametrizing the set of two-qubit X-states and a family of unitary
transformations that preserve the sparse structure of a two-qubit X-state
density matrix, we obtain the parametric form of a unitary transformation that
converts arbitrary two-qubit states into their X-counterparts. Moreover, we
provide a semi-analytic prescription on how to set the parameters of this
unitary transformation in order to preserve concurrence or negativity. We also
explicitly construct a set of X-state density matrices, parametrized by their
purity and concurrence, whose elements are in one-to-one correspondence with
the points of the concurrence versus purity (CP) diagram for generic two-qubit
states.Comment: 24 pages, 6 figures. v2 includes new references and minor changes
(accepted version
Heuristic for estimation of multiqubit genuine multipartite entanglement
For every N-qubit density matrix written in the computational basis, an
associated "X-density matrix" can be obtained by vanishing all entries out of
the main- and anti-diagonals. It is very simple to compute the genuine
multipartite (GM) concurrence of this associated N-qubit X-state, which,
moreover, lower bounds the GM-concurrence of the original (non-X) state. In
this paper, we rely on these facts to introduce and benchmark a heuristic for
estimating the GM-concurrence of an arbitrary multiqubit mixed state. By
explicitly considering two classes of mixed states, we illustrate that our
estimates are usually very close to the standard lower bound on the
GM-concurrence, being significantly easier to compute. In addition, while
evaluating the performance of our proposed heuristic, we provide the first
characterization of GM-entanglement in the steady states of the driven Dicke
model at zero temperature.Comment: 19 pages, 5 figure
Rise in the frequency of cloud cover in LANDSAT data for the period 1973 to 1981
Percentages of cloud cover in LANDSAT imagery were used to calculate the cloud cover monthly average statistic for each LANDSAT scene in Brazil, during the period of 1973 to 1981. The average monthly cloud cover and the monthly minimum cloud cover were also calculated for the regions of north, northeast, central west, southeast and south, separately
Método EPS para manejo da irrigação de forrageiras.
bitstream/CPPSE-2010/19159/1/PROCICircT63FCM2009.00422.pd
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