87 research outputs found
Paraxial propagation of a quantum charge in a random magnetic field
The paraxial (parabolic) theory of a near forward scattering of a quantum
charged particle by a static magnetic field is presented. From the paraxial
solution to the Aharonov-Bohm scattering problem the transverse transfered
momentum (the Lorentz force) is found. Multiple magnetic scattering is
considered for two models: (i) Gaussian -correlated random magnetic
field; (ii) a random array of the Aharonov-Bohm magnetic flux line. The
paraxial gauge-invariant two-particle Green function averaged with respect to
the random field is found by an exact evaluation of the Feynman integral. It is
shown that in spite of the anomalous character of the forward scattering, the
transport properties can be described by the Boltzmann equation. The Landau
quantization in the field of the Aharonov-Bohm lines is discussed.Comment: Figures and references added. Many typos corrected. RevTex, 25 pages,
9 figure
Metallo-dielectric diamond and zinc-blende photonic crystals
It is shown that small inclusions of a low absorbing metal can have a
dramatic effect on the photonic band structure. In the case of diamond and
zinc-blende photonic crystals, several complete photonic band gaps (CPBG's) can
open in the spectrum, between the 2nd-3rd, 5th-6th, and 8th-9th bands. Unlike
in the purely dielectric case, in the presence of small inclusions of a low
absorbing metal the largest CPBG for a moderate dielectric constant
(epsilon<=10) turns out to be the 2nd-3rd CPBG. The 2nd-3rd CPBG is the most
important CPBG, because it is the most stable against disorder. For a diamond
and zinc-blende structure of nonoverlapping dielectric and metallo-dielectric
spheres, a CPBG begins to decrease with an increasing dielectric contrast
roughly at the point where another CPBG starts to open--a kind of gap
competition. A CPBG can even shrink to zero when the dielectric contrast
increases further. Metal inclusions have the biggest effect for the dielectric
constant 2<=epsilon<=12, which is a typical dielectric constant at near
infrared and in the visible for many materials, including semiconductors and
polymers. It is shown that one can create a sizeable and robust 2nd-3rd CPBG at
near infrared and visible wavelengths even for a photonic crystal which is
composed of more than 97% low refractive index materials (n<=1.45, i.e., that
of silica glass or a polymer). These findings open the door for any
semiconductor and polymer material to be used as genuine building blocks for
the creation of photonic crystals with a CPBG and significantly increase the
possibilities for experimentalists to realize a sizeable and robust CPBG in the
near infrared and in the visible. One possibility is a construction method
using optical tweezers, which is analyzed here.Comment: 25 pp, 23 figs, RevTex, to appear in Phys Rev B. For more information
look at
http://www.amolf.nl/research/photonic_materials_theory/moroz/moroz.htm
Avaliação da progênie de ovelhas Merino Australiano cruzadas com carneiro Dorper ou Southdown
Relation between oral health and socioeconomic variables among schoolchildren aged 12 in the City of Manaus - AM
Produção de proteÃna microbiana e estimativas das excreções de derivados de purinas e de uréia em vacas lactantes alimentadas com rações isoprotéicas contendo diferentes nÃveis de compostos nitrogenados não-protéicos
Atributos fÃsicos, quÃmicos e biológicos relacionados com a estabilidade de agregados de dois latossolos em plantio direto no Estado de São Paulo
An Extended Age-Hardening Model for Al-Mg-Si Alloys Incorporating the Room-Temperature Storage and Cold Deformation Process Stages
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