541 research outputs found
Landau Damping in a 2D Electron Gas with Imposed Quantum Grid
Dielectric properties of semiconductor substrate with imposed two dimensional
(2D) periodic grid of quantum wires or nanotubes (quantum crossbars, QCB) are
studied. It is shown that a capacitive contact between QCB and semiconductor
substrate does not destroy the Luttinger liquid character of the long wave QCB
excitations. However, the dielectric losses of a substrate surface are
drastically modified due to diffraction processes on the QCB superlattice.
QCB-substrate interaction results in additional Landau damping regions of the
substrate plasmons. Their existence, form and the density of losses are
strongly sensitive to the QCB lattice constant.Comment: 9 pages, 12 eps-figure
The QCD vacuum, confinement and strings in the Vacuum Correlator Method
In this review paper the QCD vacuum properties and the structure of color
fields in hadrons are studied using the complete set of gauge-invariant
correlators of gluon fields. Confinement in QCD is produced by the correlators
of some certain Lorentz structure, which violate abelian Bianchi identities and
therefore are absent in the case of QED. These correlators are used to define
an effective colorless field, which satisfies Maxwell equation with nonzero
effective magnetic current. With the help of the effective field and
correlators it is shown that quarks are confined due to effective magnetic
currents, squeezing gluonic fields into a string, in agreement with the ``dual
Meissner effect''. Distribution of effective gluonic fields are plotted in
mesons, baryons and glueballs with static sources.Comment: 36 pages, 19 figures, to appear in UFN, updated version. Few
references added, minor difference
Coupled quantum wires
We study a set of crossed 1D systems, which are coupled with each other via
tunnelling at the crossings. We begin with the simplest case with no
electron-electron interactions and find that besides the expected level
splitting, bound states can emerge. Next, we include an external potential and
electron-electron interactions, which are treated within the Hartree
approximation. Then, we write down a formal general solution to the problem,
giving additional details for the case of a symmetric external potential.
Concentrating on the case of a single crossing, we were able to explain recent
experinents on crossed metallic and semiconducting nanotubes [J. W. Janssen, S.
G. Lemay, L. P. Kouwenhoven, and C. Dekker, Phys. Rev. B 65, 115423 (2002)],
which showed the presence of localized states in the region of crossing.Comment: 11 pages, 10 figure
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