2,581 research outputs found
Introduction to topological quantum computation with non-Abelian anyons
Topological quantum computers promise a fault tolerant means to perform
quantum computation. Topological quantum computers use particles with exotic
exchange statistics called non-Abelian anyons, and the simplest anyon model
which allows for universal quantum computation by particle exchange or braiding
alone is the Fibonacci anyon model. One classically hard problem that can be
solved efficiently using quantum computation is finding the value of the Jones
polynomial of knots at roots of unity. We aim to provide a pedagogical,
self-contained, review of topological quantum computation with Fibonacci
anyons, from the braiding statistics and matrices to the layout of such a
computer and the compiling of braids to perform specific operations. Then we
use a simulation of a topological quantum computer to explicitly demonstrate a
quantum computation using Fibonacci anyons, evaluating the Jones polynomial of
a selection of simple knots. In addition to simulating a modular circuit-style
quantum algorithm, we also show how the magnitude of the Jones polynomial at
specific points could be obtained exactly using Fibonacci or Ising anyons. Such
an exact algorithm seems ideally suited for a proof of concept demonstration of
a topological quantum computer.Comment: 51 pages, 51 figure
Optimized Periodic Coulomb Potential in Two Dimension
The 1/r Coulomb potential is calculated for a two dimensional system with
periodic boundary conditions. Using polynomial splines in real space and a
summation in reciprocal space we obtain numerically optimized potentials which
allow us efficient calculations of any periodic (long-ranged) potential up to
high precision. We discuss the parameter space of the optimized potential for
the periodic Coulomb potential. Compared to the analytic Ewald potential, the
optimized potentials can reach higher precisions by up to several orders of
magnitude. We explicitly give simple expressions for fast calculations of the
periodic Coulomb potential where the summation in reciprocal space is reduced
to a few terms
A Spline LR Test for Goodness-of-Fit
Goodness-of-Fit tests, nuisance parameters, cubic spline, Neyman smooth test, Lagrange Multiplier test, stable distributions, student t distributions
Thermal Emission of WASP-14b Revealed with Three Spitzer Eclipses
Exoplanet WASP-14b is a highly irradiated, transiting hot Jupiter. Joshi et
al. calculate an equilibrium temperature Teq of 1866 K for zero albedo and
reemission from the entire planet, a mass of 7.3 +/- 0.5 Jupiter masses and a
radius of 1.28 +/- 0.08 Jupiter radii. Its mean density of 4.6 g/cm3 is one of
the highest known for planets with periods less than 3 days. We obtained three
secondary eclipse light curves with the Spitzer Space Telescope. The eclipse
depths from the best jointly fit model are +/- at 4.5
{\mu}m and +/- at 8.0 {\mu}m. The corresponding brightness
temperatures are 2212 +/- 94 K and 1590 +/- 116 K. A slight ambiguity between
systematic models suggests a conservative 3.6 {\mu}m eclipse depth of
+/- and brightness temperature of 2242 +/- 55 K. Although extremely
irradiated, WASP-14b does not show any distinct evidence of a thermal
inversion. In addition, the present data nominally favor models with day night
energy redistribution less than . The current data are generally
consistent with oxygen-rich as well as carbon-rich compositions, although an
oxygen-rich composition provides a marginally better fit. We confirm a
significant eccentricity of e = 0.087 +/- 0.002 and refine other orbital
parameters.Comment: 16 pages, 16 figure
Recommended from our members
Multivariate Splines and Algebraic Geometry
Multivariate splines are effective tools in numerical analysis and approximation theory. Despite an extensive literature on the subject, there remain open questions in finding their dimension, constructing local bases, and determining their approximation power. Much of what is currently known was developed by numerical analysts, using classical methods, in particular the so-called Bernstein-B´ezier techniques. Due to their many interesting structural properties, splines have become of keen interest to researchers in commutative and homological algebra and algebraic geometry. Unfortunately, these communities have not collaborated much. The purpose of the half-size workshop is to intensify the interaction between the different groups by bringing them together. This could lead to essential breakthroughs on several of the above problems
Broadband near-infrared astronomical spectrometer calibration and on-sky validation with an electro-optic laser frequency comb
The quest for extrasolar planets and their characterisation as well as
studies of fundamental physics on cosmological scales rely on capabilities of
high-resolution astronomical spectroscopy. A central requirement is a precise
wavelength calibration of astronomical spectrographs allowing for extraction of
subtle wavelength shifts from the spectra of stars and quasars. Here, we
present an all-fibre, 400 nm wide near-infrared frequency comb based on
electro-optic modulation with 14.5 GHz comb line spacing. Tests on the
high-resolution, near-infrared spectrometer GIANO-B show a photon-noise limited
calibration precision of <10 cm/s as required for Earth-like planet detection.
Moreover, the presented comb provides detailed insight into particularities of
the spectrograph such as detector inhomogeneities and differential spectrograph
drifts. The system is validated in on-sky observations of a radial velocity
standard star (HD221354) and telluric atmospheric absorption features. The
advantages of the system include simplicity, robustness and turn-key operation,
features that are valuable at the observation sites
Exact Results for Perturbative Chern-Simons Theory with Complex Gauge Group
We develop several methods that allow us to compute all-loop partition
functions in perturbative Chern-Simons theory with complex gauge group G_C,
sometimes in multiple ways. In the background of a non-abelian irreducible flat
connection, perturbative G_C invariants turn out to be interesting topological
invariants, which are very different from finite type (Vassiliev) invariants
obtained in a theory with compact gauge group G. We explore various aspects of
these invariants and present an example where we compute them explicitly to
high loop order. We also introduce a notion of "arithmetic TQFT" and conjecture
(with supporting numerical evidence) that SL(2,C) Chern-Simons theory is an
example of such a theory.Comment: 60 pages, 9 figure
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