4,766 research outputs found
Effects of disorder on Coulomb-assisted braiding of Majorana zero modes
Majorana zero modes in one-dimensional topological superconductors obey
non-Abelian braiding statistics. Braiding manipulations can be realized by
controlling Coulomb couplings in hybrid Majorana-transmon devices. However,
strong disorder may induce accidental Majorana modes, which are expected to
have detrimental effects on braiding statistics. Nevertheless, we show that the
Coulomb-assisted braiding protocol is efficiently realized also in the presence
of accidental modes. The errors occurring during the braiding cycle are small
if the couplings of the computational Majorana modes to the accidental ones are
much weaker than the maximum Coulomb coupling.Comment: 7 pages, 4 figures, this is the final, published versio
New Symbolic Tools for Differential Geometry, Gravitation, and Field Theory
DifferentialGeometry is a Maple software package which symbolically performs
fundamental operations of calculus on manifolds, differential geometry, tensor
calculus, Lie algebras, Lie groups, transformation groups, jet spaces, and the
variational calculus. These capabilities, combined with dramatic recent
improvements in symbolic approaches to solving algebraic and differential
equations, have allowed for development of powerful new tools for solving
research problems in gravitation and field theory. The purpose of this paper is
to describe some of these new tools and present some advanced applications
involving: Killing vector fields and isometry groups, Killing tensors and other
tensorial invariants, algebraic classification of curvature, and symmetry
reduction of field equations.Comment: 42 page
Multiscale image analysis applied to gamma/hadron discrimination for VHE gamma-ray astronomy with ARGO-YBJ
Intrinsic differences in the processes involved in the development of
electromagnetic and hadronic showers in the atmosphere have been evidenced by
means of a careful analysis of the event image given by the ARGO-YBJ detector.
The images have been analyzed at different length scales and their multifractal
nature has been studied. The use of the multiscale approach together with a
properly designed and trained Artificial Neural Network, allowed us to obtain a
good gamma/hadron discrimination power. If confirmed by further studies on
different event cathegories, this result would allow to nearly double the
detector sensitivity to gamma ray sources.Comment: 10 pages, 5 figures, Presented at the "Incontro Nazionale di
Astrofisica delle Alte Energie", Rome 15-16 May 200
Statistical Topological Insulators
We define a class of insulators with gapless surface states protected from
localization due to the statistical properties of a disordered ensemble, namely
due to the ensemble's invariance under a certain symmetry. We show that these
insulators are topological, and are protected by a invariant.
Finally, we prove that every topological insulator gives rise to an infinite
number of classes of statistical topological insulators in higher dimensions.
Our conclusions are confirmed by numerical simulations.Comment: 6 pages, 1 table, 5 figures, this is the final, published versio
Topological blockade and measurement of topological charge
The fractionally charged quasiparticles appearing in the 5/2 fractional
quantum Hall plateau are predicted to have an extra non-local degree of
freedom, known as topological charge. We show how this topological charge can
block the tunnelling of these particles, and how such 'topological blockade'
can be used to readout their topological charge. We argue that the short time
scale required for this measurement is favorable for the detection of the
non-Abelian anyonic statistics of the quasiparticles. We also show how
topological blockade can be used to measure braiding statistics, and to couple
a topological qubit with a conventional one.Comment: Published version: one additional paragraph (on the 331 state); Figs.
1 and 4 modified; Ref. 46 adde
Durability testing at 5 atmospheres of advanced catalysts and catalyst supports for gas turbine engine combustors
The durability of CATCOM catalysts and catalyst supports was experimentally demonstrated in a combustion environment under simulated gas turbine engine combustor operating conditions. A test of 1000 hours duration was completed with one catalyst using no. 2 diesel fuel and operating at catalytically-supported thermal combustion conditions. The performance of the catalyst was determined by monitoring emissions throughout the test, and by examining the physical condition of the catalyst core at the conclusion of the test. Tests were performed periodically to determine changes in catalytic activity of the catalyst core. Detailed parametric studies were also run at the beginning and end of the durability test, using no. 2 fuel oil. Initial and final emissions for the 1000 hours test respectively were: unburned hydrocarbons (C3 vppm):0, 146, carbon monoxide (vppm):30, 2420; nitrogen oxides (vppm):5.7, 5.6
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