38,548 research outputs found
Noncommutative tori and universal sets of non-binary quantum gates
A problem of universality in simulation of evolution of quantum system and in
theory of quantum computations is related with the possibility of expression or
approximation of arbitrary unitary transformation by composition of specific
unitary transformations (quantum gates) from given set. In an earlier paper
(quant-ph/0010071) application of Clifford algebras to constructions of
universal sets of binary quantum gates was shown. For
application of a similar approach to non-binary quantum gates
in present work is used rational noncommutative torus . A
set of universal non-binary two-gates is presented here as one example.Comment: 5 pages, REVTeX3.1, v2: spelling and misprints, 4 new ref
Quadratic solitary waves in a counterpropagating quasi-phase-matched configuration
We demonstrate the possibility of self-trapping of optical beams by use of
quasi phase matching in a counterpropagating configuration in quadratic media.
We also show the predominant stability of these spatial self-guided beams and
estimate the power level required for their experimental observation.Comment: 3 pages, 4 figure
Astrokit -- an Efficient Program for High-Precision Differential CCD Photometry and Search for Variable Stars
Having a need to perform differential photometry for tens of thousands stars
in a several square degrees field, we developed Astrokit program. The software
corrects the star brightness variations caused by variations of atmospheric
transparency: to this end, the program selects for each star an individual
ensemble of reference stars having similar magnitudes and positions in the
frame. With ten or more reference stars in the ensemble, the differences
between their spectral types and the spectral type of the object studied become
unimportant. Astrokit searches for variable stars using Robust Median
Statistics criterion, which allows candidate variables to be selected more
efficiently than by analyzing the standard deviation of star magnitudes. The
software allows very precise automatic analysis of long inhomogeneous sets of
photometric observations of a large number of objects to be performed, making
it possible to find "hot Jupiter" type exoplanet transits and low-amplitude
variables. We describe the algorithm of the program and the results of its
application to reduce the data of the photometric sky survey in Cygnus as well
as observations of the open cluster NGC188 and the transit of the exoplanet
WASP-11 b / HAT-P-10 b, performed with the MASTER-II-URAL telescope of the
Kourovka Astronomical Observatory of the Ural Federal University.Comment: to be published in Astrophysical Bulletin, Vol. 69, No.
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