5,011 research outputs found
Prometheus unbound: A study of the Dallas/Fort Worth Regional Airport
The history of the controversies in the development of the Dallas/Fort Worth Regional Airport is detailed. Present technological and organizational management problems are outlined. Maps and illustrations are included
Technology and politics: The regional airport experience
The findings of a comparative study of the following six regional airports were presented: Dallas/Fort Worth, Kansas City, Washington, D.C., Montreal, Tampa, and St. Louis. Each case was approached as a unique historical entity, in order to investigate common elements such as: the use of predictive models in planning, the role of symbolism to heighten dramatic effects, the roles of community and professional elites, and design flexibility. Some of the factors considered were: site selection, consolidation of airline service, accessibility, land availability and cost, safety, nuisance, and pollution constraints, economic growth, expectation of regional growth, the demand forecasting conundrum, and design decisions. The hypotheses developed include the following: the effect of political, social, and economic conflicts, the stress on large capacity and dramatic, high-technology design, projections of rapid growth to explain the need for large capital outlays
Quantum Chaos, Delocalization, and Entanglement in Disordered Heisenberg Models
We investigate disordered one- and two-dimensional Heisenberg spin lattices
across a transition from integrability to quantum chaos from both a statistical
many-body and a quantum-information perspective. Special emphasis is devoted to
quantitatively exploring the interplay between eigenvector statistics,
delocalization, and entanglement in the presence of nontrivial symmetries. The
implications of basis dependence of state delocalization indicators (such as
the number of principal components) is addressed, and a measure of {\em
relative delocalization} is proposed in order to robustly characterize the
onset of chaos in the presence of disorder. Both standard multipartite and {\em
generalized entanglement} are investigated in a wide parameter regime by using
a family of spin- and fermion- purity measures, their dependence on
delocalization and on energy spectrum statistics being examined. A distinctive
{\em correlation between entanglement, delocalization, and integrability} is
uncovered, which may be generic to systems described by the two-body random
ensemble and may point to a new diagnostic tool for quantum chaos. Analytical
estimates for typical entanglement of random pure states restricted to a proper
subspace of the full Hilbert space are also established and compared with
random matrix theory predictions.Comment: 17 pages, 10 figures, revised versio
Ultrasensitive Beam Deflection Measurement via Interferometric Weak Value Amplification
We report on the use of an interferometric weak value technique to amplify
very small transverse deflections of an optical beam. By entangling the beam's
transverse degrees of freedom with the which-path states of a Sagnac
interferometer, it is possible to realize an optical amplifier for polarization
independent deflections. The theory for the interferometric weak value
amplification method is presented along with the experimental results, which
are in good agreement. Of particular interest, we measured the angular
deflection of a mirror down to 560 femtoradians and the linear travel of a
piezo actuator down to 20 femtometers
Precision frequency measurements with interferometric weak values
We demonstrate an experiment which utilizes a Sagnac interferometer to
measure a change in optical frequency of 129 kHz per root Hz with only 2 mW of
continuous wave, single mode input power. We describe the measurement of a weak
value and show how even higher frequency sensitivities may be obtained over a
bandwidth of several nanometers. This technique has many possible applications,
such as precision relative frequency measurements and laser locking without the
use of atomic lines.Comment: 4 pages, 3 figures, published in PR
Optimizing the Signal to Noise Ratio of a Beam Deflection Measurement with Interferometric Weak Values
The amplification obtained using weak values is quantified through a detailed
investigation of the signal to noise ratio for an optical beam deflection
measurement. We show that for a given deflection, input power and beam radius,
the use of interferometric weak values allows one to obtain the optimum signal
to noise ratio using a coherent beam. This method has the advantage of reduced
technical noise and allows for the use of detectors with a low saturation
intensity. We report on an experiment which improves the signal to noise ratio
for a beam deflection measurement by a factor of 54 when compared to a
measurement using the same beam size and a quantum limited detector
Rapidly reconfigurable optically induced photonic crystals in hot rubidium vapor
Through periodic index modulation, we create two different types of photonic
structures in a heated rubidium vapor for controlled reflection, transmission
and diffraction of light. The modulation is achieved through the use of the AC
Stark effect resulting from a standing-wave control field. The periodic
intensity structures create translationally invariant index profiles analogous
to photonic crystals in spectral regions of steep dispersion. Experimental
results are consistent with modeling.Comment: 6 pages, 6 figure
Continuous phase amplification with a Sagnac interferometer
We describe a weak value inspired phase amplification technique in a Sagnac
interferometer. We monitor the relative phase between two paths of a slightly
misaligned interferometer by measuring the average position of a split-Gaussian
mode in the dark port. Although we monitor only the dark port, we show that the
signal varies linearly with phase and that we can obtain similar sensitivity to
balanced homodyne detection. We derive the source of the amplification both
with classical wave optics and as an inverse weak value.Comment: 5 pages, 4 figures, previously submitted for publicatio
Interferometric weak value deflections: quantum and classical treatments
We derive the weak value deflection given in a paper by Dixon et al. (Phys.
Rev. Lett. 102, 173601 (2009)) both quantum mechanically and classically. This
paper is meant to cover some of the mathematical details omitted in that paper
owing to space constraints
A search for thermal X-ray signatures in Gamma-Ray Bursts I: Swift bursts with optical supernovae
The X-ray spectra of Gamma-Ray Bursts can generally be described by an
absorbed power law. The landmark discovery of thermal X-ray emission in
addition to the power law in the unusual GRB 060218, followed by a similar
discovery in GRB 100316D, showed that during the first thousand seconds after
trigger the soft X-ray spectra can be complex. Both the origin and prevalence
of such spectral components still evade understanding, particularly after the
discovery of thermal X-ray emission in the classical GRB 090618. Possibly most
importantly, these three objects are all associated with optical supernovae,
begging the question of whether the thermal X-ray components could be a result
of the GRB-SN connection, possibly in the shock breakout. We therefore
performed a search for blackbody components in the early Swift X-ray spectra of
11 GRBs that have or may have associated optical supernovae, accurately
recovering the thermal components reported in the literature for GRBs 060218,
090618 and 100316D. We present the discovery of a cooling blackbody in GRB
101219B/SN2010ma, and in four further GRB-SNe we find an improvement in the fit
with a blackbody which we deem possible blackbody candidates due to
case-specific caveats. All the possible new blackbody components we report lie
at the high end of the luminosity and radius distribution. GRB 101219B appears
to bridge the gap between the low-luminosity and the classical GRB-SNe with
thermal emission, and following the blackbody evolution we derive an expansion
velocity for this source of order 0.4c. We discuss potential origins for the
thermal X-ray emission in our sample, including a cocoon model which we find
can accommodate the more extreme physical parameters implied by many of our
model fits.Comment: 16 pages, 6 figures, accepted for MNRA
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