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 Найдено в других БД:Каталог книг и брошюр библиотеки ИФ СО РАН (5)
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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Rotter I., Sadreev A. F.
Заглавие : Zeros in single-channel transmission through double quantum dots
Место публикации : Phys. Rev. E: AMERICAN PHYSICAL SOC, 2005. - Vol. 71, Is. 4. - Ст.46204. - ISSN 1063-651X, DOI 10.1103/PhysRevE.71.046204
Примечания : Cited References: 28
Предметные рубрики: PHASE EVOLUTION
RESONANCE
TRANSPORT
SYSTEMS
Ключевые слова (''Своб.индексиров.''): fano interference--fano resonances--overlapping resonances--transmission amplitude--channel capacity--eigenvalues and eigenfunctions--function evaluation--hamiltonians--mathematical models--mathematical operators--matrix algebra--resonance--signal interference--semiconductor quantum dots
Аннотация: By using a simple model we consider single-channel transmission through a double quantum dot that consists of two single dots coupled by a wire of finite length L. Each of the two single dots is characterized by a few energy levels only, and the wire is assumed to have only one level whose energy depends on the length L. The transmission is described by using S matrix theory and the effective non-Hermitian Hamilton operator H-eff of the system. The decay widths of the eigenstates of H-eff depend strongly on energy. The model explains the origin of the transmission zeros of the double dot that is considered by us. Mostly, they are caused by (destructive) interferences between neighboring levels and are of first order. When, however, both single dots are identical and their transmission zeros are of first order, those of the double dot are of second order. First-order transmission zeros cause phase jumps of the transmission amplitude by pi, while there are no phase jumps related to second-order transmission zeros. In this latter case, a phase jump occurs due to the fact that the width of one of the states vanishes when crossing the energy of the transmission zero. The parameter dependence of the widths of the resonance states is determined by the spectral properties of the two single dots.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Erkaev N. V., Shaidurov V. A., Semenov V. S., Langmayr D., Biernat H. K.
Заглавие : Peculiarities of Alfven wave propagation along a nonuniform magnetic flux tube
Место публикации : Phys. Plasmas: AMER INST PHYSICS, 2005. - Vol. 12, Is. 1. - Ст.12905. - ISSN 1070-664X, DOI 10.1063/1.1833392
Примечания : Cited References: 18
Предметные рубрики: HYDROMAGNETIC-WAVES
TRANSFER EVENTS
FIELD
SLOW
Ключевые слова (''Своб.индексиров.''): algebra--approximation theory--boundary conditions--electric conductivity--electric field effects--integral equations--magnetic flux--magnetohydrodynamics--perturbation techniques--polarization--vectors--velocity measurement--alfven wave propagation--axial symmetry--magnetic flux tubes--magnetosonic pulses--wave propagation
Аннотация: Within the framework of the assumption of large azimuthal wave numbers, the equations for Alfven and slow magnetosonic waves are obtained using frozen-in material coordinates. These equations are specified for the case of a nonuniform magnetic field with axial symmetry. Assuming a meridional polarization of the magnetic field and velocity perturbations, the effects of Alfven wave propagation are analyzed which are related to geometric characteristics of a nonuniform magnetic field: (a) A finite curvature radius of the magnetic field lines and (b) convergence of magnetic field lines. The interaction between the Alfven and magnetosonic waves is found to be strongly dependent on the curvature radius of the magnetic tube and the local plasma beta parameter. The electric field amplitude and the length scale of a wave front are found to increase very strongly in the course of the Alfven wave propagation along a converging magnetic flux tube. Also studied is a temporal decrease of the wave perturbations which is caused by dissipation at the conducting boundary. (C) 2005 American Institute of Physics.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Rotter I., Sadreev A. F.
Заглавие : Influence of branch points in the complex plane on the transmission through double quantum dots
Место публикации : Phys. Rev. E: AMER PHYSICAL SOC, 2004. - Vol. 69, Is. 6. - Ст.66201. - ISSN 1539-3755, DOI 10.1103/PhysRevE.69.066201
Примечания : Cited References: 25
Предметные рубрики: ELECTRON-ATOM SCATTERING
S-MATRIX
DOUBLE POLES
CONTINUUM
SYSTEM
MODEL
Ключевые слова (''Своб.индексиров.''): eigenvalues and eigenfunctions--hamiltonians--mathematical models--matrix algebra--probability--resonance--scattering--wave propagation--branch points--open quantum systems--propagating modes--quantum computing devices--semiconductor quantum dots
Аннотация: We consider single-channel transmission through a double quantum dot system consisting of two single dots that are connected by a wire and coupled each to one lead. The system is described in the framework of the S matrix theory by using the effective Hamiltonian of the open quantum system. It consists of the Hamiltonian of the closed system (without attached leads) and a term that accounts for the coupling of the states via the continuum of propagating modes in the leads. This model allows one to study the physical meaning of branch points in the complex plane. They are points of coalesced eigenvalues and separate the two scenarios with avoided level crossings and without any crossings in the complex plane. They influence strongly the features of transmission through double quantum dots.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Luna-Acosta G. A., Mendez-Bermudez J. A., Seba P., Pichugin K. N.
Заглавие : Classical versus quantum structure of the scattering probability matrix: Chaotic waveguides
Место публикации : Phys. Rev. E: AMER PHYSICAL SOC, 2002. - Vol. 65, Is. 4. - Ст.46605. - ISSN 1539-3755, DOI 10.1103/PhysRevE.65.046605
Примечания : Cited References: 47
Предметные рубрики: SEMICLASSICAL CROSS-SECTION
CONDUCTANCE FLUCTUATIONS
S-MATRIX
BALLISTIC-TRANSPORT
WEAK-LOCALIZATION
CAVITIES
COLLISIONS
MICROSTRUCTURES
DENSITY
CHANNEL
Ключевые слова (''Своб.индексиров.''): chaos theory--matrix algebra--optical waveguides--quantum theory--scattering--wave equations--chaotic cavities--chaotic waveguides--quantum structure--scattering probability matrix--quantum optics
Аннотация: The purely classical counterpart of the scattering probability matrix (SPM) \S(n,m)\(2) of the quantum scattering matrix S is defined for two-dimensional quantum waveguides for an arbitrary number of propagating modes M. We compare the quantum and classical structures of \S(n,m)\(2) for a waveguide with generic Hamiltonian chaos. It is shown that even for a moderate number of channels, knowledge of the classical structure of the SPM allows us to predict the global structure of the quantum one and, hence, understand important quantum transport properties of waveguides in terms of purely classical dynamics. It is also shown that the SPM, being an intensity measure, can give additional dynamical information to that obtained by the Poincare maps.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fransson J., Eriksson O., Johansson B., Sandalov I. S.
Заглавие : On the non-orthogonality problem in the description of quantum devices
Коллективы : International Conference on Nonequilibrium Carrier Dynamics in Semiconductors
Место публикации : Physica B/ International Conference on Nonequilibrium Carrier Dynamics in Semiconductors (11 ; 1999 ; July ; 19-23 ; Kyoto, Japan). - 1999. - Vol. 272, Is. 1-4. - P.28-30. - ISSN 0921-4526, DOI 10.1016/S0921-4526(99)00343-9
Примечания : Cited References: 8
Предметные рубрики:
Ключевые слова (''Своб.индексиров.''): non-orthogonality--current--tunneling--correlation methods--electric contacts--electric currents--electron energy levels--electron tunneling--equations of motion--green's function--mathematical operators--matrix algebra--hubbard operators--potential barriers--tunneling currents--semiconductor quantum dots
Аннотация: An approach which allows to include the corrections from non-orthogonality of electron states in contacts and quantum dots is developed. Comparison of the energy levels and charge distributions of electrons in 1D quantum dot (QD) in equilibrium, obtained within orthogonal (OR) and non-orthogonal representations (NOR), with the exact ones shows that the NOR provides a considerable improvement, for levels below the top of barrier. The approach is extended to non-equilibrium states. A derivation of the tunneling current through a single potential barrier is performed using equations of motion for correlation functions. A formula for transient current derived by means of the diagram technique for Hubbard operators is given for the problem of QD with strongly correlated electrons interacting with electrons in contacts. The non-orthogonality renormalizes the tunneling matrix elements and spectral weights of Green functions. (C) 1999 Elsevier Science B.V. All rights reserved.
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