2,823 research outputs found
Use of entanglement in quantum optics
Several recent demonstrations of two-particle interferometry are reviewed and shown to be examples of either color entanglement or beam entanglement. A device, called a number filter, is described and shown to be of value in preparing beam entanglements. Finally, we note that all three concepts (color and beam entaglement, and number filtering) may be extended to three or more particles
MASE: A New Data--Reduction Pipeline for the Magellan Echellette Spectrograph
We introduce a data reduction package written in Interactive Data Language
(IDL) for the Magellan Echellete Spectrograph (MAGE). MAGE is a
medium-resolution (R ~4100), cross-dispersed, optical spectrograph, with
coverage from ~3000-10000 Angstroms. The MAGE Spectral Extractor (MASE)
incorporates the entire image reduction and calibration process, including bias
subtraction, flat fielding, wavelength calibration, sky subtraction, object
extraction and flux calibration of point sources. We include examples of the
user interface and reduced spectra. We show that the wavelength calibration is
sufficient to achieve ~5 km/s RMS accuracy and relative flux calibrations
better than 10%. A light-weight version of the full reduction pipeline has been
included for real-time source extraction and signal-to-noise estimation at the
telescope.Comment: 10 pages (ApJ format), accepted PAS
Fast hashing with Strong Concentration Bounds
Previous work on tabulation hashing by Patrascu and Thorup from STOC'11 on
simple tabulation and from SODA'13 on twisted tabulation offered Chernoff-style
concentration bounds on hash based sums, e.g., the number of balls/keys hashing
to a given bin, but under some quite severe restrictions on the expected values
of these sums. The basic idea in tabulation hashing is to view a key as
consisting of characters, e.g., a 64-bit key as characters of
8-bits. The character domain should be small enough that character
tables of size fit in fast cache. The schemes then use tables
of this size, so the space of tabulation hashing is . However, the
concentration bounds by Patrascu and Thorup only apply if the expected sums are
.
To see the problem, consider the very simple case where we use tabulation
hashing to throw balls into bins and want to analyse the number of
balls in a given bin. With their concentration bounds, we are fine if ,
for then the expected value is . However, if , as when tossing
unbiased coins, the expected value is for large data sets,
e.g., data sets that do not fit in fast cache.
To handle expectations that go beyond the limits of our small space, we need
a much more advanced analysis of simple tabulation, plus a new tabulation
technique that we call \emph{tabulation-permutation} hashing which is at most
twice as slow as simple tabulation. No other hashing scheme of comparable speed
offers similar Chernoff-style concentration bounds.Comment: 54 pages, 3 figures. An extended abstract appeared at the 52nd Annual
ACM Symposium on Theory of Computing (STOC20
A note on monopole moduli spaces
We discuss the structure of the framed moduli space of Bogomolny monopoles
for arbitrary symmetry breaking and extend the definition of its stratification
to the case of arbitrary compact Lie groups. We show that each stratum is a
union of submanifolds for which we conjecture that the natural metric is
hyperKahler. The dimensions of the strata and of these submanifolds are
calculated, and it is found that for the latter, the dimension is always a
multiple of four.Comment: 17 pages, LaTe
Sonoluminescing air bubbles rectify argon
The dynamics of single bubble sonoluminescence (SBSL) strongly depends on the
percentage of inert gas within the bubble. We propose a theory for this
dependence, based on a combination of principles from sonochemistry and
hydrodynamic stability. The nitrogen and oxygen dissociation and subsequent
reaction to water soluble gases implies that strongly forced air bubbles
eventually consist of pure argon. Thus it is the partial argon (or any other
inert gas) pressure which is relevant for stability. The theory provides
quantitative explanations for many aspects of SBSL.Comment: 4 page
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