7,396 research outputs found
Formation and interaction of resonance chains in the open 3-disk system
In ballistic open quantum systems one often observes that the resonances in
the complex-energy plane form a clear chain structure. Taking the open 3-disk
system as a paradigmatic model system, we investigate how this chain structure
is reflected in the resonance states and how it is connected to the underlying
classical dynamics. Using an efficient scattering approach we observe that
resonance states along one chain are clearly correlated while resonance states
of different chains show an anticorrelation. Studying the phase space
representations of the resonance states we find that their localization in
phase space oscillate between different regions of the classical trapped set as
one moves along the chains and that these oscillations are connected to a
modulation of the resonance spacing. A single resonance chain is thus no WKB
quantization of a single periodic orbits, but the structure of several
oscillating chains arises from the interaction of several periodic orbits. We
illuminate the physical mechanism behind these findings by combining the
semiclassical cycle expansion with a quantum graph model.Comment: 25 pages, 15 figure
Selective enhancement of topologically induced interface states in a dielectric resonator chain
The recent realization of topological phases in insulators and
superconductors has advanced the quest for robust quantum technologies. The
prospects to implement the underlying topological features controllably has
given incentive to explore optical platforms for analogous realizations. Here
we realize a topologically induced defect state in a chain of dielectric
microwave resonators and show that the functionality of the system can be
enhanced by supplementing topological protection with non-hermitian symmetries
that do not have an electronic counterpart. We draw on a characteristic
topological feature of the defect state, namely, that it breaks a sublattice
symmetry. This isolates the state from losses that respect parity-time
symmetry, which enhances its visibility relative to all other states both in
the frequency and in the time domain. This mode selection mechanism naturally
carries over to a wide range of topological and parity-time symmetric optical
platforms, including couplers, rectifiers and lasers.Comment: 5 pages, 4 figures, + supplementary information (3 pages, 4 figures
Probing Localization in Absorbing Systems via Loschmidt Echos
We measure Anderson localization in quasi-one-dimensional waveguides in the
presence of absorption by analyzing the echo dynamics due to small
perturbations. We specifically show that the inverse participation number of
localized modes dictates the decay of the Loschmidt echo, differing from the
Gaussian decay expected for diffusive or chaotic systems. Our theory, based on
a random matrix modeling, agrees perfectly with scattering echo measurements on
a quasi one-dimensional microwave cavity filled with randomly distributed
scatterers.Comment: cross-reference with nonlin.CD-Chaotic Dynamic
Algebraic fidelity decay for local perturbations
From a reflection measurement in a rectangular microwave billiard with
randomly distributed scatterers the scattering and the ordinary fidelity was
studied. The position of one of the scatterers is the perturbation parameter.
Such perturbations can be considered as {\em local} since wave functions are
influenced only locally, in contrast to, e. g., the situation where the
fidelity decay is caused by the shift of one billiard wall. Using the
random-plane-wave conjecture, an analytic expression for the fidelity decay due
to the shift of one scatterer has been obtained, yielding an algebraic
decay for long times. A perfect agreement between experiment and theory has
been found, including a predicted scaling behavior concerning the dependence of
the fidelity decay on the shift distance. The only free parameter has been
determined independently from the variance of the level velocities.Comment: 4 pages, 5 figure
Endemic microorganisms of a Drosophila simulans strain and their relationships with the non-mendelian transmission of a character
International audienc
Utilization of Drought-Stricken Corn Silage by Yearling Steers
Corn silage is a very versatile and palatable feed that fits well into many cattle feeding programs. Insufficient rainfall in several areas of the country in recent years has resulted in many additional acres of corn being ensiled due to the low potential grain yield. Harvesting drought-stricken corn silage results in at least partial salvage of the crop. However, many farmers have expressed concern about the feeding value of drought-damaged corn silage and how it can be best incorporated into feedlot rations for optimal performance and maximal economic return
Effect of Cement Dust and Reimplanting on Finishing Heifer Performance
Eighty crossbred yearling heifers were used to determine the possible benefit of including 2% cement kiln dust in a typical high-concentrate finishing ration. The value of reimplanting with Ralgro during a 151-day feeding period was also evaluated. Cattle on the cement dust ration gained 13% slower and ate 6.3% less feed per day than control heifers, resulting in an 8.5% poorer feed conversion with cement dust. Carcass quality and yield grades were not affected by cement dust in the ration. In this study, no benefit was observed from implanting heifers twice during a 151-day feeding period as compared with a single implant in terms of finishing trial performance or carcass characteristics
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