134,713 research outputs found
Fluoroether modified epoxy composites
Addition of controlled amounts of perfluorinated alkyl ether diacyl fluoride to epoxy resin systems prior to cure results in a formulation which, exhibits improved energy absorbing properties
Forcing nonperiodicity with a single tile
An aperiodic prototile is a shape for which infinitely many copies can be
arranged to fill Euclidean space completely with no overlaps, but not in a
periodic pattern. Tiling theorists refer to such a prototile as an "einstein"
(a German pun on "one stone"). The possible existence of an einstein has been
pondered ever since Berger's discovery of large set of prototiles that in
combination can tile the plane only in a nonperiodic way. In this article we
review and clarify some features of a prototile we recently introduced that is
an einstein according to a reasonable definition. [This abstract does not
appear in the published article.]Comment: 18 pages, 10 figures. This article has been substantially revised and
accepted for publication in the Mathematical Intelligencer and is scheduled
to appear in Vol 33. Citations to and quotations from this work should
reference that publication. If you cite this work, please check that the
published form contains precisely the material to which you intend to refe
Topologically Robust Transport of Photons in a Synthetic Gauge Field
Electronic transport in low dimensions through a disordered medium leads to
localization. The addition of gauge fields to disordered media leads to
fundamental changes in the transport properties. For example, chiral edge
states can emerge in two-dimensional systems with a perpendicular magnetic
field. Here, we implement a "synthetic'' gauge field for photons using
silicon-on-insulator technology. By determining the distribution of transport
properties, we confirm the localized transport in the bulk and the suppression
of localization in edge states, using the "gold standard'' for localization
studies. Our system provides a new platform to investigate transport properties
in the presence of synthetic gauge fields, which is important both from the
fundamental perspective of studying photonic transport and for applications in
classical and quantum information processing.Comment: 4.5 pages, 3 figures and supplementary materia
Planetary radar
The radar astronomy activities supported by the Deep Space Network are reported. The high power S- and X-band radar transmitters at the Goldstone 64 meter station were used for a radar probe of Mars during January, February, and March 1980, which was designed to provide range and Doppler data derived from signals reflected from the Martian surface, taking advantage of the planet's nearness during opposition
Interference susceptibility of satellite 136 MHz telemetry link
Interference susceptibility of satellite 136 MHz telemetry lin
Fault-tolerant Quantum Communication with Minimal Physical Requirements
We describe a novel protocol for a quantum repeater which enables long
distance quantum communication through realistic, lossy photonic channels.
Contrary to previous proposals, our protocol incorporates active purification
of arbitrary errors at each step of the protocol using only two qubits at each
repeater station. Because of these minimal physical requirements, the present
protocol can be realized in simple physical systems such as solid-state single
photon emitters. As an example, we show how nitrogen vacancy color centers in
diamond can be used to implement the protocol, using the nuclear and electronic
spin to form the two qubits.Comment: 4 pages, 3 figures. V2: Minor modifications. V3: Major changes in the
presentation and new titl
Fundamental constraints on particle tracking with optical tweezers
A general quantum limit to the sensitivity of particle position measurements
is derived following the simple principle of the Heisenberg microscope. The
value of this limit is calculated for particles in the Rayleigh and Mie
scattering regimes, and with parameters which are relevant to optical tweezers
experiments. The minimum power required to observe the zero-point motion of a
levitating bead is also calculated, with the optimal particle diameter always
smaller than the wavelength. We show that recent optical tweezers experiments
are within two orders of magnitude of quantum limited sensitivity, suggesting
that quantum optical resources may soon play an important role in high
sensitivity tracking applications
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