4,225 research outputs found
Remote Sensing of Giant Reed with QuickBird Satellite Imagery
QuickBird high resolution (2.8 m) satellite imagery was
evaluated for distinguishing giant reed (
Arundo donax
L.) infestations
along the Rio Grande in southwest Texas. (PDF has 5 pages.
Light Reflectance Characteristics and Remote Sensing of Waterlettuce
Waterlettuce (
Pistia stratiotes
L.) is a free-floating exotic
aquatic weed that often invades and clogs waterways in the
southeastern United States. A study was conducted to evaluate
the potential of using remote sensing technology to distinguish
infestations of waterlettuce in Texas waterways. Field
reflectance measurements showed that waterlettuce had
higher visible green reflectance than associated plant species.
Waterlettuce could be detected in both aerial color- infrared
(CIR) photography and videography where it had
light pink to pinkish-white image tonal responses. Computer
analysis of CIR photographic and videographic images had
overall accuracy assessments of 86% and 84%, respectively. (PDF contains 6 pages.
Guidance and Control in a Josephson Charge Qubit
In this paper we propose a control strategy based on a classical guidance law
and consider its use for an example system: a Josephson charge qubit. We
demonstrate how the guidance law can be used to attain a desired qubit state
using the standard qubit control fields.Comment: 9 pages, 5 figure
Estimating total standing herbaceous biomass production with LANDSAT MSS digital data
Rangeland biomass data were correlated with spectral vegetation indices, derived from LANDSAT MSS data. LANDSAT data from five range and three other land use sites in Willacv and Cameron Counties were collected on October 17 and December 10, 1975, and on July 31 and September 23, 1976. The overall linear correlation of total standing herbaceous biomass with the LANDSAT derived perpendicular vegetation index was highly significant (r = 0.90**) for these four dates. The standard error of estimate was 722 kg/ha. Biomass data were recorded for two of these range sites for 8 months (March through October) during the 1976 growing season. Standing green biomass accounted for most of the increase in herbage, starting in June and ending about September and October. These results indicate that satellite data may be useful for the estimation of total standing herbaceous biomass production that could aid range managers in assessing range condition and animal carrying capacities of large and inaccessible range holdings
Signatures of the collapse and revival of a spin Schr\"{o}dinger cat state in a continuously monitored field mode
We study the effects of continuous measurement of the field mode during the
collapse and revival of spin Schr\"{o}dinger cat states in the Tavis-Cummings
model of N qubits (two-level quantum systems) coupled to a field mode. We show
that a compromise between relatively weak and relatively strong continuous
measurement will not completely destroy the collapse and revival dynamics while
still providing enough signal-to-noise resolution to identify the signatures of
the process in the measurement record. This type of measurement would in
principle allow the verification of the occurrence of the collapse and revival
of a spin Schr\"{o}dinger cat state.Comment: 5 pages, 2 figure
Nonlinear backreaction in a quantum mechanical SQUID
In this paper we discuss the coupling between a quantum mechanical
superconducting quantum interference device (SQUID) and an applied static
magnetic field. We demonstrate that the backreaction of a SQUID on the applied
field can interfere with the ability to bias the SQUID at values of the static
(DC) magnetic flux at, or near to, transitions in the quantum mechanical SQUID.Comment: 9 pages, to be published in Phys. Rev.
Recovery of classical chaotic-like behaviour in a quantum three body problem
Recovering trajectories of quantum systems whose classical counterparts display chaotic behaviour has been a subject that has received a lot of interest over the last decade. However, these studies have focused on driven dissipative systems. The relevance and impact of chaotic-like phenomena to quantum systems has been highlighted in recent studies which have shown that quantum chaos is significant in some aspects of quantum computation and information processing. In this paper we study a three body system comprising of identical particles arranged so that the system's classical trajectories exhibit Hamiltonian chaos. Here we show that it is possible to recover very nearly classical-like chaotic trajectories from such a system through an unravelling of the master equation
On open quantum systems, effective Hamiltonians and device characterization
High fidelity models, which support accurate device characterization and
correctly account for environmental effects, are crucial to the engineering of
scalable quantum technologies. As it ensures positivity of the density matrix,
one preferred model for open systems describes the dynamics with a master
equation in Lindblad form. The Linblad operators are rarely derived from first
principles, resulting in dynamical models which miss those additional terms
that must generally be added to bring the master equation into Lindblad form,
together with concomitant other terms that must be assimilated into an
effective Hamiltonian. In first principles derivations such additional terms
are often cancelled (countered), frequently in an ad hoc manner. In the case of
a Superconducting Quantum Interference Device (SQUID) coupled to an Ohmic bath,
the resulting master equation implies the environment has a significant impact
on the system's energy. We discuss the prospect of keeping or cancelling this
impact; and note that, for the SQUID, measuring the magnetic susceptibility
under control of the capacitive coupling strength and the externally applied
flux, results in experimentally measurable differences between models. If this
is not done correctly, device characterization will be prone to systemic
errors.Comment: 5 pages, 3 figure
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