31 research outputs found
Creating Metastable Schrodinger Cat States
We propose a scheme using feedback to generate a macroscopic quantum superposition of coherent states in an optical cavity mode which experiences very little decoherence (due to dissipation)
Adiabatic Elimination in Compound Quantum Systems with Feedback
Feedback in compound quantum systems is effected by using the output from one
sub-system (``the system'') to control the evolution of a second sub-system
(``the ancilla'') which is reversibly coupled to the system. In the limit where
the ancilla responds to fluctuations on a much shorter time scale than does the
system, we show that it can be adiabatically eliminated, yielding a master
equation for the system alone. This is very significant as it decreases the
necessary basis size for numerical simulation and allows the effect of the
ancilla to be understood more easily. We consider two types of ancilla: a
two-level ancilla (e.g. a two-level atom) and an infinite-level ancilla (e.g.
an optical mode). For each, we consider two forms of feedback: coherent (for
which a quantum mechanical description of the feedback loop is required) and
incoherent (for which a classical description is sufficient). We test the
master equations we obtain using numerical simulation of the full dynamics of
the compound system. For the system (a parametric oscillator) and feedback
(intensity-dependent detuning) we choose, good agreement is found in the limit
of heavy damping of the ancilla. We discuss the relation of our work to
previous work on feedback in compound quantum systems, and also to previous
work on adiabatic elimination in general.Comment: 18 pages, 12 figures including two subplots as jpeg attachment
Decoherence, Re-coherence, and the Black Hole Information Paradox
We analyze a system consisting of an oscillator coupled to a field. With the
field traced out as an environment, the oscillator loses coherence on a very
short {\it decoherence timescale}; but, on a much longer {\it relaxation
timescale}, predictably evolves into a unique, pure (ground) state. This
example of {\it re-coherence} has interesting implications both for the
interpretation of quantum theory and for the loss of information during black
hole evaporation. We examine these implications by investigating the
intermediate and final states of the quantum field, treated as an open system
coupled to an unobserved oscillator.Comment: 23 pages, 2 figures included, figures 3.1 - 3.3 available at
http://qso.lanl.gov/papers/Papers.htm
Ponderomotive Control of Quantum Macroscopic Coherence
It is shown that because of the radiation pressure a Schr\"odinger cat state
can be generated in a resonator with oscillating wall. The optomechanical
control of quantum macroscopic coherence and its detection is taken into
account introducing new cat states. The effects due to the environmental
couplings with this nonlinear system are considered developing an operator
perturbation procedure to solve the master equation for the field mode density
operator.Comment: Latex,22 pages,accepted by Phys.Rev.
Farming Equipment and Methods
Photograph of the Soil Conservation Service Station, Guthrie, OK. A view of controlled plots and metereological instruments. OK-R-11
Water Conservation; Water Erosion; Flooding and Prevention
Photograph of a view showing catchment in contour furrows constructed with a 16 inch sulky plow (2 rounds in a furrow), June 1937. The snow is 6 inches deep in the furrows. OK-R-53
Farming Equipment and Methods
Photograph of the Soil Conservation Service Station, Guthrie, OK. A view of controlled plots and metereological instruments (erosion picture)
Farming Equipment and Methods
Photograph of the Red Plains Experiment Station, Guthrie, OK. Showing blue gama grass. Fully mature. OK-R-28
Recommended from our members
Vegetational Responses Following Control of Sand Shinnery Oak with Tebuthiuron
Tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thia-diazol-2-yl]-N,N′-dimethylurea} pellets were applied aerially in April 1979 at rates of 0.5 and 1.0 kg ai./ha to rangelands supporting a uniform stand of sand shinnery oak (Quercus havardii Rydb.) near Andrews, Texas. Tebuthiuron pellets were applied at 1.1 kg ai/ha to a second location near Jayton, Texas, in March 1980. Sand shinnery oak was significantly reduced (P is lesser than or equal to 0.05) in treated plots at both locations. Yields of annual and perennial grasses were significantly greater (P is lesser than or equal to 0.05) and those of forbs significantly less (P is less than or equal to 0.05) on tebuthiuron-treated plots at Andrews. Untreated plots at Andrews had more bare soil than those treated with tebuthiuron after 18 and 30 months. Grass yields at the Jayton site were greater, although no significant (P is less than or equal to 0.05) differences occurred with forb yields.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202
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Ecological Factors Affecting the Abundance and Cultural Control of the Pink Bollworm
This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project