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AbstractAbstract
[en] The interaction of a Gaussian mode with a homogeneous and an inhomogeneous laser transition is described. The interaction of the beam with the medium in a laser is treated by taking into account the spatial distribution of both radiation and gain. The intensity characteristics are very different from those obtained for a one-dimensional interaction of a plane wave with a saturating medium. In the presence of a small-signal gain profile the threshold condition requires much higher inversion densities along the optic axis than by ignoring this profile. For gas lasers, for instance, having a small-signal gain profile that is approximately described by a zero-order Bessel function, the threshold inversion density can be about 50 percent higher. For high-power systems the saturation of the medium by the Gaussian intensity distribution results in a considerable amount of radial radiation transport. For homogeneous transitions this amount is about equal to the stimulated emission and for inhomogeneous transitions it is about half of it, independent of the beamwidth. Further, it is found that if one slowly passes the threshold condition for laser action, the intensity jumps from zero to a certain value and vice versa. This effect has also been verified experimentally. (auth)
Primary Subject
Record Type
Journal Article
Journal
IEEE (Inst. Electr. Electron. Eng.) J. Quant. Electron; v. QE-11(5); p. 198-204
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Davalos, David; Pineda, Carlos; Moreno, Camilo; Urbina, Juan-Diego, E-mail: davidphysdavalos@gmail.com2020
AbstractAbstract
[en] We study one-mode Gaussian quantum channels in continuous-variable systems by performing a black-box characterization using complete positivity and trace preserving conditions, and report the existence of two subsets that do not have a functional Gaussian form. Our study covers as a particular limit the case of singular channels, thus connecting our results with their known classification scheme based on canonical forms. Our full characterization of Gaussian channels without Gaussian functional form is completed by showing how Gaussian states are transformed under these operations, and by deriving the conditions for the existence of master equations for the non-singular cases. We show that although every functional form can be found in the vicinity of the identity, one of them does not parametrize unitary channels. (paper)
Primary Subject
Source
Available from http://dx.doi.org/10.1088/1751-8121/abb1e3; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Journal of Physics. A, Mathematical and Theoretical (Online); ISSN 1751-8121;
; v. 53(42); [15 p.]

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Yue, Chen; Zhijun, Ren; Baojin, Peng; Yongsheng, Dong, E-mail: renzhijun@zjnu.cn2018
AbstractAbstract
[en] We introduce a group of virtual sources for generating Lommel–Gauss beams based on beam superposition to analyze nonparaxial propagation. We typically derive the paraxial approximation and integral representations of the nth-order Lommel–Gauss beams. The first three orders of the nonparaxial corrections for the on-axis field of the Lommel–Gauss beams are analytically obtained. The on-axis intensity distribution of the corresponding nonparaxial corrections is also provided. (paper)
Primary Subject
Source
Available from http://dx.doi.org/10.1088/2040-8986/aad6f4; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Journal of Optics (Online); ISSN 2040-8986;
; v. 20(9); [5 p.]

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Brito, A.L. de; Vyas, R.
Proceedings of the 14. National Meeting on Condensed Matter Physics. v.21991
Proceedings of the 14. National Meeting on Condensed Matter Physics. v.21991
AbstractAbstract
[en] Published in summary form only
Primary Subject
Source
Sociedade Brasileira de Fisica, Sao Paulo, SP (Brazil); 201 p; 1991; p. 261; 14. National Meeting on Condensed Matter Physics; Caxambu, MG (Brazil); 7-11 May 1991
Record Type
Miscellaneous
Literature Type
Conference
Report Number
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Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
[en] The distribution of masses for neutron stars is analyzed using the Bayesian statistical inference, evaluating the likelihood of two a priori gaussian peaks distribution by using fifty-five measured points obtained in a variety of systems. The results strongly suggest the existence of a bimodal distribution of the masses, with the first peak around 1.35M⊙ ± 0.06M⊙ and a much wider second peak at 1.73M⊙ ± 0.36M⊙. We compared the two gaussian's model centered at 1.35M⊙ and 1.55M⊙ against a "single gaussian" model with 1.50M⊙ ± 0.11M⊙ using 3σ that provided a wide peak covering objects the full range of observed of masses. In order to compare models, BIC (Baysesian Information Criterion) can be used and a strong evidence for two distributions model against one peak model was found. The results support earlier views related to the different evolutionary histories of the members for the first two peaks, which produces a natural separation (in spite that no attempt to "label" the systems has been made). However, the recently claimed low-mass group, possibly related to O - Mg - Ne core collapse events, has a monotonically decreasing likelihood and has not been identified within this sample. (author)
Primary Subject
Source
STARS 2011: 1. Caribbean symposium on nuclear and astroparticle physics; Havana (Cuba); 1-4 May 2011; Available from DOI: http://dx.doi.org/10.1142/S0218301311040268
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Journal Article
Literature Type
Conference
Journal
International Journal of Modern Physics E; ISSN 0218-3013;
; v. 20(supp.1); p. 203-207

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Lupo, Cosmo; Mancini, Stefano; Pirandola, Stefano; Aniello, Paolo, E-mail: cosmo.lupo@unicam.it, E-mail: pirs@cs.york.ac.uk, E-mail: paolo.aniello@na.infn.it, E-mail: stefano.mancini@unicam.it2011
AbstractAbstract
[en] The set of quantum Gaussian channels acting on one bosonic mode can be classified according to the action of the group of Gaussian unitaries. We look for bounds on the classical capacity for channels belonging to such a classification. Lower bounds can be efficiently calculated by restricting the study to Gaussian encodings, for which we provide analytical expressions.
Primary Subject
Source
CEWQO10: 17. Central European Workshops on Quantum Optics; St Andrews, Scotland (United Kingdom); 6-11 Jun 2010; Available from http://dx.doi.org/10.1088/0031-8949/2011/T143/014016; Country of input: International Atomic Energy Agency (IAEA)
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Journal Article
Literature Type
Conference
Journal
Physica Scripta (Online); ISSN 1402-4896;
; v. 2011(T143); [6 p.]

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Delorme, Mathieu; Rosso, Alberto; Wiese, Kay Jörg, E-mail: wiese@lpt.ens.fr2017
AbstractAbstract
[en] In the theory of extreme values of Gaussian processes, many results are expressed in terms of the Pickands constant . This constant depends on the local self-similarity exponent α of the process, i.e. locally it is a fractional Brownian motion (fBm) of Hurst index . Despite its importance, only two values of the Pickands constant are known: and . Here, we extend the recent perturbative approach to fBm to include drift terms. This allows us to investigate the Pickands constant around standard Brownian motion () and to derive the new exact result . (letter)
Primary Subject
Source
Available from http://dx.doi.org/10.1088/1751-8121/aa5c98; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Journal of Physics. A, Mathematical and Theoretical (Online); ISSN 1751-8121;
; v. 50(16); [13 p.]

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Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
Novello, M.; Guimaraes, M.E.X.; Svaiter, N.F.
Proceedings of the 11. National Meeting on Particle Physics and Fields1990
Proceedings of the 11. National Meeting on Particle Physics and Fields1990
AbstractAbstract
[en] Published in summary form only
Original Title
Sistemas de coordenadas gaussianas no universe de Goedel
Primary Subject
Source
Sociedade Brasileira de Fisica, Rio de Janeiro, RJ (Brazil); 72 p; 1990; p. 57; 11. National Meeting on Particle Physics and Fields; Caxambu, MG (Brazil); 26-30 Sep 1990; Available from the Library of Comissao Nacional de Energia Nuclear, RJ, Brazil
Record Type
Miscellaneous
Literature Type
Conference
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AbstractAbstract
No abstract available
Primary Subject
Source
Available from http://dx.doi.org/10.1070/RM2005v060n01ABEH000817; Abstract only; Country of input: International Atomic Energy Agency (IAEA)
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Journal Article
Journal
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AbstractAbstract
No abstract available
Primary Subject
Source
Available from http://dx.doi.org/10.3367/UFNe.0182.201204f.0442; Abstract only; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Physics Uspekhi; ISSN 1063-7869;
; v. 55(4); p. 412-420

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