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Interference (wave propagation)

About: Interference (wave propagation) is a research topic. Over the lifetime, 26086 publications have been published within this topic receiving 321110 citations.


Papers
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Journal ArticleDOI
TL;DR: It is shown that a smart jammer should be present in all subbands and a sufficient condition that forces the jammer to spread its interference signal on the whole communicator frequency band is given.
Abstract: Frequency diversity for a phase-coherent frequency-hopping spread-spectrum system is proposed. The frequency band of the communicator is partitioned into L disjoint subbands on which L replicas of the communicator signal are simultaneously transmitted; each signal replica hops independently in its subband. Therefore, both phase continuity and coherent optimal combining of the received replicas are possible. Optimum diversity is thus at least 6 dB better than the conventional noncoherent FH-SS system. We show that a smart jammer should be present in all subbands. We also give a sufficient condition that forces the jammer to spread its interference signal on the whole communicator frequency band.

69 citations

Journal ArticleDOI
TL;DR: Three photons can display qualitatively new interference phenomena such as genuine three-photon interference, and this work shows how to isolate three- photon interference with more than 90 % visibility, completely suppressing two-photons and single-Photon interference.
Abstract: Multiparticle quantum interference is critical for our understanding and exploitation of quantum information, and for fundamental tests of quantum mechanics. A remarkable example of multi-partite correlations is exhibited by the Greenberger-Horne-Zeilinger (GHZ) state. In a GHZ state, three particles are correlated while no pairwise correlation is found. The manifestation of these strong correlations in an interferometric setting has been studied theoretically since 1990 but no three-photon GHZ interferometer has been realized experimentally. Here we demonstrate three-photon interference that does not originate from two-photon or single photon interference. We observe phase-dependent variation of three-photon coincidences with (92.7±4.6)% visibility in a generalized Franson interferometer using energy-time entangled photon triplets. The demonstration of these strong correlations in an interferometric setting provides new avenues for multiphoton interferometry, fundamental tests of quantum mechanics, and quantum information applications in higher dimensions.

69 citations

Journal ArticleDOI
TL;DR: In this paper, the mean sound levels resulting from the interference between direct waves and those reflected from the ground are strongly influenced, especially at frequencies near interference minima, by fluctuations in phase and amplitude of the sound waves induced by propagation through atmospheric turbulence.
Abstract: The mean sound levels resulting from the interference between direct waves and those reflected from the ground are strongly influenced, especially at frequencies near interference minima, by fluctuations in phase and amplitude of the sound waves induced by propagation through atmospheric turbulence. Since it was found experimentally that the correlation length (∠1.1 m) of the meteorological fluctuations is comparable to the separation between the interfering sound paths, previous theoretical work by Ingard and Maling [J. Acoust. Soc. Am. 35, 1056–1058 (1963)] has been extended to allow for partial covariance between the two waves. The theory has been further extended to use the calculations of fluctuations in phase and amplitude of spherical waves, and to include the explicit calculation of the fluctuating acoustical index of refraction from the fluctuating values of temperature and wind velocity. Measurements (1–6 kHz) have been made of the interference spectrum at 15, 30, and 45 m from a point source 1....

69 citations

Journal ArticleDOI
TL;DR: In this paper, three and four input multiports in a three dimensional glass platform, fabricated using the femtosecond laser direct-write technique, were demonstrated and a full quantum characterization was performed.
Abstract: We demonstrate three and four input multiports in a three dimensional glass platform, fabricated using the femtosecond laser direct-write technique. Hong-Ou-Mandel (HOM) interference is observed and a full quantum characterization is performed, obtaining two photon correlation matrices for all combinations of input and output ports. For the 3-port case, the quantum visibilities are accurately predicted solely from measurement of the classical coupling ratios.

69 citations

Patent
13 Jan 1987
TL;DR: In this article, the optimum correlation between measured and known values of transmittance or reflectance determines the property or identity of a sample, where three or more discrete radiation components can be selected which are transmitted or reflected by relatively different amounts due to interference, absorption or scatter, thereby enabling fewer radiation components to be used to provide an accurate result.
Abstract: In the method and apparatus, optimum correlation between measured and known values of transmittance or reflectance determines the property or identity of a sample. Three or more discrete radiation components can be selected which are transmitted or reflected by relatively different amounts due to interference, absorption or scatter, thereby enabling fewer radiation components to be used to provide an accurate result. The known values can be derived by analogue or digital techniques, the digital technique employing a model or models taking account of absorption, interference and/or scatter. Techniques are disclosed for reducing computing time by range ajustment, identification of a zero correlation value in a differential function of the model or models and computation of correlation coefficients for two or more groups of radiation components.

69 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202213
2021840
20201,221
20191,432
20181,351
20171,311