169,776 research outputs found
Quantum Radar
No full textWe propose a quantum metrology protocol for the localization of a noncooperative pointlike target in three-dimensional space, by illuminating it with electromagnetic waves. It employs all the spatial degrees of freedom of N entangled photons to achieve an uncertainty in localization that is N times smaller for each spatial direction than what could be achieved by N-independent photons or by classical light of the same average intensity
Protecting the Moon farside radio-telescopes from RFI produced at the future Lagrangian-Points space stations
No full text
State estimation: A comparison between direct state measurement and tomography
No full textWe compare direct state measurement (DSM, or weak state tomography) to conventional state reconstruction (tomography) through accurate Monte Carlo simulations. We find that DSM is much less precise than tomography, but it is surprisingly robust to its inherent bias, which introduces an unavoidable error in the reconstruction. In addition to studying DSM and proposing a method to estimate such bias from the experimental data, we show that the number of DSM measurements can be optimized and that the dimensionality of the DSM pointer is irrelevant: Both finite- and infinite-dimensional pointers provide comparable reconstructions
Exoplanet Searches by Future Deep Space Missions
No full textThe search for exoplanets could benefit from gravitational lensing if we could get to 550 AU from the Sun and beyond. This is because the gravitational lens of the Sun would highly intensify there any weak electromagnetic wave reaching the solar system from distant planets in the Galaxy (see Maccone 2009). The gravitational lens of the Sun, however, has a drawback: the solar Corona. Electrons in the Corona make electromagnetic waves diverge and this pushes the focus out to distances higher than 550 AU. Jupiter is the second larger mass in the solar system after the Sun, but in this focal game not only the mass matters: rather, what really matters is the ratio between the radius of the body squared and the mass of the body. In this regard, Jupiter qualifies as the second best choice for a space mission, requiring the spacecraft to reach 6,077 AU. In this paper, we study the benefit of exoplanet searches by deep space missions
Use as stabilizers of perfluoropolyether oils at high temperatures, higher than 200°C, of compounds not containing phosphorrocess.
No full textUse as stabilizers of perfluoropolyether oils at high temperatures, higher than 200° C, of compounds not containing phosphor and having the general formula (A): wherein: X, Y, X', Y', equal to or different, are indenpendently the one from the other H; NO2; C1-C4 alkyl; C1-C4 alkoxy, preferably methoxy group; Z = -CH2-; > C=0 (carbonyl); m and n are integers such that m is in the range 0-80, extremes included; n is in the range 0-20, extremes included, m+n being > 1; the molecular weight of the perfluoropolyether part (units with indexes m and n) being from 500 to 10,000, preferably from 1,000 to 4,000. Also published as: EP1354932 (A1), US7081440 (B2), US2003203823 (A1), JP2003327985 (A), EP1354932 (B1
Multiqubit noise deconvolution and characterization
No full textWe present a noise deconvolution technique for obtaining noiseless expectation values of noisy observables at the output of multiqubit quantum channels. For any number of qubits or in the presence of correlations, our protocol applies to any mathematically invertible noise model, even when its inverse map is not physically implementable, i.e., when it is neither completely positive nor trace preserving. For a generic observable affected by Pauli noise it provides a quadratic speedup, always producing a rescaling of its Pauli basis components. We show that it is still possible to achieve the deconvolution while experimentally estimating the noise parameters, whenever these are unknown (bypassing resource-heavy techniques such as quantum process tomography). We provide a simulation, with examples for both Pauli and non-Pauli channels
High-dimensional methods for quantum homodyne tomography
No full textWe provide optimized recursion relations for homodyne tomography. We improve previous methods by mitigating the divergences intrinsic in the calculation of the pattern functions used previously, and detail how to implement the data analysis through Monte Carlo simulations. Our refinements are necessary for the reconstruction of excited quantum states which populate a high-dimensional subspace of the electromagnetic field Hilbert space. (C) 2022 Elsevier B.V. All rights reserved
Additives for perfluoropolyether oils
No full textAbstract
Use as stabilizers of perfluoropolyether oils at high temperatures, higher than 200.degree. C., of compounds not containing phosphor and having the general formula (A): ##STR00001#
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