3,519 research outputs found
Type I superconductivity in the Dirac semimetal PdTe2
The superconductor PdTe was recently classified as a Type II Dirac
semimetal, and advocated to be an improved platform for topological
superconductivity. Here we report magnetic and transport measurements conducted
to determine the nature of the superconducting phase. Surprisingly, we find
that PdTe is a Type I superconductor with K and a critical
field mT. Our crystals also exhibit the intermediate
state as demonstrated by the differential paramagnetic effect. For we
observe superconductivity of the surface sheath. This calls for a close
examination of superconductivity in PdTe in view of the presence of
topological surface states.Comment: 5 page
Oxidation and protection of fiberglass-epoxy composite masts for photovoltaic arrays in the low Earth orbital environment
Fiberglass-epoxy composites are considered for use as structural members for the mast of the space station solar array panel. The low Earth orbital environment in which space station is to operate is composed mainly of atomic oxygen, which has been shown to cause erosion of many organic materials and some metals. Ground based testing in a plasma asher was performed to determine the extent of degradation of fiberglass-epoxy composites when exposed to a simulated atomic oxygen environment. During exposure, the epoxy at the surface of the composite was oxidized, exposing individual glass fibers which could easily be removed. Several methods of protecting the composite were evaluated in an atomic oxygen environment and with thermal cycling and flexing. The protection techniques evaluated to date include an aluminum braid covering, an indium-tin eutectic and a silicone based paint. The open aluminum braid offered little protection while the CV-1144 coating offered some initial protection against atomic oxygen, but appears to develop cracks which accelerate degradation when flexed. Coatings such as the In-Sn eutectic may provide adequate protection by containing the glass fibers even though mass loss still occurs
Dynamics of Metal Centers Monitored by Nuclear Inelastic Scattering
Nuclear inelastic scattering of synchrotron radiation has been used now since
10 years as a tool for vibrational spectroscopy. This method has turned out
especially useful in case of large molecules that contain a M\"ossbauer active
metal center. Recent applications to iron-sulfur proteins, to iron(II) spin
crossover complexes and to tin-DNA complexes are discussed. Special emphasis is
given to the combination of nuclear inelastic scattering and density functional
calculations
Gate fidelity fluctuations and quantum process invariants
We characterize the quantum gate fidelity in a state-independent manner by
giving an explicit expression for its variance. The method we provide can be
extended to calculate all higher order moments of the gate fidelity. Using
these results we obtain a simple expression for the variance of a single qubit
system and deduce the asymptotic behavior for large-dimensional quantum
systems. Applications of these results to quantum chaos and randomized
benchmarking are discussed.Comment: 13 pages, no figures, published versio
Compactness properties of operator multipliers
We continue the study of multidimensional operator multipliers initiated in
[arXiv:math/0701645]. We introduce the notion of the symbol of an operator
multiplier. We characterise completely compact operator multipliers in terms of
their symbol as well as in terms of approximation by finite rank multipliers.
We give sufficient conditions for the sets of compact and completely compact
multipliers to coincide and characterise the cases where an operator multiplier
in the minimal tensor product of two C*-algebras is automatically compact. We
give a description of multilinear modular completely compact completely bounded
maps defined on the direct product of finitely many copies of the C*-algebra of
compact operators in terms of tensor products, generalising results of Saar
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