2,868 research outputs found
A Wang-Landau method for calculating Renyi entropies in finite-temperature quantum Monte Carlo simulations
We implement a Wang-Landau sampling technique in quantum Monte Carlo (QMC)
for the purpose of calculating the Renyi entanglement entropies and associated
mutual information. The algorithm converges an estimate for an analogue to the
density of states for Stochastic Series Expansion QMC allowing a direct
calculation of Renyi entropies without explicit thermodynamic integration. We
benchmark results for the mutual information on two-dimensional (2D) isotropic
and anisotropic Heisenberg models, 2D transverse field Ising model, and 3D
Heisenberg model, confirming a critical scaling of the mutual information in
cases with a finite-temperature transition. We discuss the benefits and
limitations of broad sampling techniques compared to standard importance
sampling methods.Comment: 9 pages, 7 figure
Geometric mutual information at classical critical points
A practical use of the entanglement entropy in a 1d quantum system is to
identify the conformal field theory describing its critical behavior. It is
exactly for an interval of length in an infinite system,
where is the central charge of the conformal field theory. Here we define
the geometric mutual information, an analogous quantity for classical critical
points. We compute this for 2d conformal field theories in an arbitrary
geometry, and show in particular that for a rectangle cut into two rectangles,
it is proportional to . This makes it possible to extract in classical
simulations, which we demonstrate for the critical Ising and 3-state Potts
models.Comment: 5 pages. v3: published versio
Hidden Broad Line Seyfert 2 Galaxies in the CfA and 12micron Samples
We report the results of a spectropolarimetric survey of the CfA and 12micron
samples of Seyfert 2 galaxies (S2s). Polarized (hidden) broad line regions
(HBLRs) are confirmed in a number of galaxies, and several new cases
(F02581-1136, MCG -3-58-7, NGC 5995, NGC 6552, NGC 7682) are reported. The
12micron S2 sample shows a significantly higher incidence of HBLR (50%) than
its CfA counterpart (30%), suggesting that the latter may be incomplete in
hidden AGNs. Compared to the non-HBLR S2s, the HBLR S2s display distinctly
higher radio power relative to their far-infrared output and hotter dust
temperature as indicated by the f25/f60 color. However, the level of
obscuration is indistinguishable between the two types of S2. These results
strongly support the existence of two intrinsically different populations of
S2: one harboring an energetic, hidden S1 nucleus with BLR, and the other, a
``pure S2'', with weak or absent S1 nucleus and a strong, perhaps dominating
starburst component. Thus, the simple purely orientation-based unification
model is not applicable to all Seyfert galaxies.Comment: 5 pages with embedded figs, ApJ Letters, in pres
El Consulado de Cádiz y el Reglamento de Comercio Libre en 1765
Tomo I ; pág. 79-9
Jumble Java Byte Code to Measure the Effectiveness of Unit Tests
Jumble is a byte code level mutation testing tool for Java which inter-operates with JUnit. It has been designed to operate in an industrial setting with large projects. Heuristics have been included to speed the checking of mutations, for example, noting which test fails for each mutation and running this first in subsequent mutation checks. Significant effort has been put into ensuring that it can test code which uses custom class loading and reflection. This requires careful attention to class path handling and coexistence with foreign class-loaders. Jumble is currently used on a continuous basis within an agile programming environment with approximately 370,000 lines of Java code under source control. This checks out project code every fifteen minutes and runs an incremental set of unit tests and mutation tests for modified classes. Jumble is being made available as open source
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