14,537 research outputs found
Quantum Memristors in Quantum Photonics
We propose a method to build quantum memristors in quantum photonic
platforms. We firstly design an effective beam splitter, which is tunable in
real-time, by means of a Mach-Zehnder-type array with two equal 50:50 beam
splitters and a tunable retarder, which allows us to control its reflectivity.
Then, we show that this tunable beam splitter, when equipped with weak
measurements and classical feedback, behaves as a quantum memristor. Indeed, in
order to prove its quantumness, we show how to codify quantum information in
the coherent beams. Moreover, we estimate the memory capability of the quantum
memristor. Finally, we show the feasibility of the proposed setup in integrated
quantum photonics
Genus and spot density in the COBE DMR first year anisotropy maps
A statistical analysis of texture on the {\it COBE}-DMR first year sky maps
based on the genus and spot number is presented. A generalized
statistic is defined in terms of ``observable'' quantities: the genus and spot
density that would be measured by different cosmic observers. This strategy
together with the use of Monte Carlo simulations of the temperature
fluctuations, including all the relevant experimental parameters, represent the
main difference with previous analyses. Based on the genus analysis we find a
strong anticorrelation between the quadrupole amplitude and the
spectral index of the density fluctuation power spectrum at recombination
of the form K for fixed
, consistent with previous works. The result obtained based on the spot
density is consistent with this relation. In addition to the
previous results we have determined, using Monte Carlo simulations, the minimum
uncertainty due to cosmic variance for the determination of the spectral index
with the genus analysis. This uncertainty is .Comment: 5 pages, uuencode file containing text and 1 figure. MNRAS in press
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