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Volumetric Calibration Refinement using masked back projection and image correlation superposition
This paper deals with a new, reconstruction based, approach of refining a volumetric calibration. The technique is based on a 2D cross-correlation between particle images on the sensor plane with a planar back projection from a tomographic reconstruction in the same sensor plane to determine potential disparities between the initial camera calibration and the measurement. Additive superposition of the correlation maps from different sets or particle images allows reducing the influence of noise and ghost particles such that the systematic errors in the calibration can be corrected. The different sections describe the theory, the principle processing steps and the convergence of the procedure. Furthermore, the concept is proven by simulating the entire process of the measurement chain, with the help of a synthetic comparison. The results show that disparities of over 9 pixels could be corrected to an average of below 0.1 pixels during the refinement steps. Finally, the technique demonstrates it´s potential to measured data, where the numbers of outliers in the raw results are reduced after the volumetric calibration refinement
Projective filtering of a single spatial radiation eigenmode
Lossless filtering of a single coherent (Schmidt) mode from spatially
multimode radiation is a problem crucial for optics in general and for quantum
optics in particular. It becomes especially important in the case of
nonclassical light that is fragile to optical losses. An example is bright
squeezed vacuum generated via high-gain parametric down conversion or four-wave
mixing. Its highly multiphoton and multimode structure offers a huge increase
in the information capacity provided that each mode can be addressed
separately. However, the nonclassical signature of bright squeezed vacuum,
photon-number correlations, are highly susceptible to losses. Here we
demonstrate lossless filtering of a single spatial Schmidt mode by projecting
the spatial spectrum of bright squeezed vacuum on the eigenmode of a
single-mode fiber. Moreover, we show that the first Schmidt mode can be
captured by simply maximizing the fiber-coupled intensity. Importantly, the
projection operation does not affect the targeted mode and leaves it usable for
further applications.Comment: 10 pages, 9 figure
Three Puzzles on Mathematics, Computation, and Games
In this lecture I will talk about three mathematical puzzles involving
mathematics and computation that have preoccupied me over the years. The first
puzzle is to understand the amazing success of the simplex algorithm for linear
programming. The second puzzle is about errors made when votes are counted
during elections. The third puzzle is: are quantum computers possible?Comment: ICM 2018 plenary lecture, Rio de Janeiro, 36 pages, 7 Figure
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