scholarly journals Non-Hermitian Hamiltonians and Quantum Transport in Multi-Terminal Conductors

Entropy ◽  
2020 ◽  
Vol 22 (4) ◽  
pp. 459
Author(s):  
Nikolay Shubin ◽  
Alexander Gorbatsevich ◽  
Gennadiy Krasnikov
Keyword(s):  
Quantum Interference ◽  
Bound States ◽  
Tight Binding ◽  
Detailed Comparison ◽  
Tight Binding Approximation ◽  
Transmission Coefficients ◽  
Compact Expression ◽  
Electrode Insertion ◽  
Hermitian Structures ◽  
Non Equilibrium Green’S Function

We study the transport properties of multi-terminal Hermitian structures within the non-equilibrium Green’s function formalism in a tight-binding approximation. We show that non-Hermitian Hamiltonians naturally appear in the description of coherent tunneling and are indispensable for the derivation of a general compact expression for the lead-to-lead transmission coefficients of an arbitrary multi-terminal system. This expression can be easily analyzed, and a robust set of conditions for finding zero and unity transmissions (even in the presence of extra electrodes) can be formulated. Using the proposed formalism, a detailed comparison between three- and two-terminal systems is performed, and it is shown, in particular, that transmission at bound states in the continuum does not change with the third electrode insertion. The main conclusions are illustratively exemplified by some three-terminal toy models. For instance, the influence of the tunneling coupling to the gate electrode is discussed for a model of quantum interference transistor. The results of this paper will be of high interest, in particular, within the field of quantum design of molecular electronic devices.

THERMAL SOLITONS AND SOLECTRONS IN 1D ANHARMONIC LATTICES UP TO PHYSIOLOGICAL TEMPERATURES

2008 ◽  
Vol 18 (12) ◽  
pp. 3815-3823 ◽  
Author(s):  
M. G. VELARDE ◽  
W. EBELING ◽  
A. P. CHETVERIKOV
Keyword(s):  
Bound States ◽  
Tight Binding ◽  
Langevin Equations ◽  
Thermal Excitation ◽  
Tight Binding Approximation ◽  
Physiological Level ◽  
Wide Range ◽  
Electron Distributions ◽  
Lattice Coupling ◽  
Soliton Dynamic

We study the thermal excitation of solitons in 1D Toda–Morse lattices in a wide range of temperatures from zero up to physiological level (about 300 K) and their influence on added excess electrons moving on the lattice. The lattice units are treated by classical Langevin equations. The electron distributions are in a first estimate represented by equilibrium adiabatic distributions in the actual fields. Further, the electron dynamics is modeled in the framework of the tight-binding approximation including on-site energy shifts due to electron-lattice coupling and stochastic hopping between the sites. We calculate the electron distributions and discuss the excitations of solectron type (electron-soliton dynamic bound states) and estimate their life times.

Electronic bound states at the surface of a metal

1952 ◽  
Vol 48 (3) ◽  
pp. 457-469 ◽  
Author(s):  
G. R. Baldock
Keyword(s):  
Crystal Structures ◽  
Small Groups ◽  
Bound States ◽  
Tight Binding ◽  
Surface States ◽  
Tight Binding Approximation ◽  
Cubic Lattice ◽  
Simple Cubic ◽  
Simple Cubic Lattice ◽  
Lattice Geometry

AbstractThe conditions under which bound states associated with atoms in the surface of a metal may exist are investigated, using the tight-binding approximation. These states arise as a result of modifications in the parameters of certain atoms. The modifications required to produce (a) bound states associated with all the atoms in the surface (surface states) and (b) bound states associated with particular small groups of atoms are found for the simple cubic lattice. It is also shown that most of the simpler crystal structures do not exhibit surface states without such modifications; in the graphite and diamond lattices, however, surface states exist solely by virtue of the lattice geometry.

scholarly journals Fermions in the Rindler spacetime

2019 ◽  
Vol 16 (09) ◽  
pp. 1950140 ◽  
Author(s):  
L. C. N. Santos ◽  
C. C. Barros
Keyword(s):  
Differential Equation ◽  
Wave Equation ◽  
Energy Spectrum ◽  
Dirac Equation ◽  
Reference Frame ◽  
Bound States ◽  
Liouville Problem ◽  
External Potential ◽  
Compact Expression ◽  
Sturm Liouville

In this paper, we study the Dirac equation in the Rindler spacetime. The solution of the wave equation in an accelerated reference frame is obtained. The differential equation associated to this wave equation is mapped into a Sturm–Liouville problem of a Schrödinger-like equation. We derive a compact expression for the energy spectrum associated with the Dirac equation in an accelerated reference. It is shown that the noninertial effect of the accelerated reference frame mimics an external potential in the Dirac equation and, moreover, allows the formation of bound states.

Electrical Transport Properties of Carbon Nanotube Metal-Semiconductor Heterojunction

2016 ◽  
Vol 15 (05n06) ◽  
pp. 1660009 ◽  
Author(s):  
Keka Talukdar ◽  
Anil Shantappa
Keyword(s):  
Electrical Transport ◽  
Nearest Neighbor ◽  
Electronic Devices ◽  
Tight Binding ◽  
Transmission Function ◽  
Topological Defects ◽  
Dynamics Simulation ◽  
Internal Stresses ◽  
Electrical Transport Properties ◽  
Tight Binding Approximation

Carbon nanotubes (CNTs) have been proved to have promising applicability in various fields of science and technology. Their fascinating mechanical, electrical, thermal, optical properties have caught the attention of today’s world. We have discussed here the great possibility of using CNTs in electronic devices. CNTs can be both metallic and semiconducting depending on their chirality. When two CNTs of different chirality are joined together via topological defects, they may acquire rectifying diode property. We have joined two tubes of different chiralities through circumferential Stone–Wales defects and calculated their density of states by nearest neighbor tight binding approximation. Transmission function is also calculated to analyze whether the junctions can be used as electronic devices. Different heterojunctions are modeled and analyzed in this study. Internal stresses in the heterojunctions are also calculated by molecular dynamics simulation.

Luminescent Amorphous Silicon Layers

1997 ◽  
Vol 486 ◽  
Author(s):  
G. Allan ◽  
C. Delerue ◽  
M. Lannoo
Keyword(s):  
Electronic Structure ◽  
Amorphous Silicon ◽  
Radiative Recombination ◽  
Crystalline Silicon ◽  
Tight Binding ◽  
Blue Shift ◽  
Localized States ◽  
Structure Model ◽  
Radiative Recombination Rate ◽  
Tight Binding Approximation

AbstractThe electronic structure of amorphous silicon layers has been calculated within the empirical tight binding approximation using the Wooten-Winer-Weaire atomic structure model. We predict an important blue shift due to the confinement for layer thickness below 3 nm and we compare with crystalline silicon layers. The radiative recombination rate is enhanced by the disorder and the confinement but remains quite small. The comparison of our results with experimental results shows that the density of defects and localized states in the studied samples must be quite small.

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