Eric R Hedin

• Ph.D.
• Professor (Associate) at Ball State University

The objective of this paper is to design impedance surfaces for the solution of the problem of electromagnetic compatibility of antennas. In a recent paper, corresponding surfaces were used to reduce coupling between antennas located on a plane. These surfaces were made artificially, e.g., by loading a conducting surface with corrugations. The desi...

The transmission and the circular transmission are investigated for a ring of quantum dots (in a benzene-type configuration) connected to external leads in the meta-configuration. A computational method utilizing the tight-binding approximation to the Schrödinger equation is used to solve for the transmission probabilities as a function of the elec...

A double-stranded DNA molecule subject to a perpendicular gating electric field and a small mechanical strain exhibits a negative differential resistance (NDR) in its current–voltage (I–V) characteristics. Using an advanced two-dimensional tight-binding model including hopping integrals for the next nearest-neighbors, we implement perturbative stra...

This article explores a new approach of localization using a novel hyperbolic method in an external environment. This method is compared with the conventional hyperbolic method. Two cases are considered: propagation in line of sight (LOS) and non-line of sight (NLOS) environments. The algorithm used here integrates a probabilistic approach which is...

new scenario for the occurrence of a Fano resonance in the transmission probability of electron waveguides is investigated using a coupled-channel theory. Both a quantum dot and an antidot with either short- or finite-range interaction are embedded in the electron waveguide. Particularly, when the Fano resonance occurs close to the mobility edge (c...

Based on a theory of extra dimensional confinement of quantum particles [E. R. Hedin, Physics Essays 25, 2 (2012)], a simple model of a nucleon-nucleon (NN) central potential is derived which quantitatively reproduces the radial profile of other models, without adjusting any free parameters. It is postulated that a higher-dimensional simple harmoni...

Electron transport through a linear array of nanoscopic rings with six quantum dot sites per ring is investigated in the presence of an external magnetic flux producing an Aharonov-Bohm phase shift effect. A tight-binding model is employed to analytically calculate the transmission as a function of electron energy, external flux, and inter-site cou...

Transmission properties are investigated for a system of two-branch nanorings with two quantum dots per branch. The rings are connected serially by a linear segment, creating a chain of rings. Applying a tight-binding Hamiltonian method, the electron transmission properties are primarily studied. Multiple system parameters are varied to study their...

Transmission properties of a linear chain of nanorings with 6 quantum dots (QD) per ring are investigated with and without magnetic field effects. The rings are connected serially by a linear segment. A tightbinding Hamiltonian is solved exactly, giving the transmission for any number of rings in series. The Aharonov-Bohm effect shifts and splits t...

The problem of analysis of the electromagnetic field behaviour from the open end of the parallel-plate waveguide with infinite impedance flanges is theoretically investigated. The case with the absence of impedance flanges is also considered. Furthermore, we take into account particular features of the waveguide edges. The effects of the impedance...

Multiple, serially-connected nanoscale rings are analyzed using a tight-binding computational algorithm which allows calculation of the transmission and current characteristics of the system as a function of energy and external magnetic flux. Results show the role of bilateral symmetry in the system response to imposed flux, which can shift the sys...

A defective double stranded poly(dG)-poly(dC) DNA molecule under axial mechanical strain is analyzed using a tight-binding computational model which allows calculation of the transmission and current characteristics of the system as a function of electron energy. Results show the existence of highly sensitive electron transmission behavior with res...

Based on a theory of extra dimensional confinement of quantum particles [E. R. Hedin, Physics Essays, 2012, 25(2): 177], a simple model of a nucleon-nucleon (NN) central potential is derived which quantitatively reproduces the radial profile of other models, without adjusting any free parameters. It is postulated that a higher-dimensional simple ha...

We investigate transmission resonances and conductance properties of multiple, serially connected, direct-contact nanoscale rings using the tight-binding model. Quantum dots (QDs) are embedded in the two arms of each ring, and Zeeman-splitting of the QD energy levels is incorporated into the system Hamiltonian. Transmission bands develop as the num...

This paper provides a solution for the design problem of a two-dimensional infinite impedance cylinder structure. This structure must reduce surface waves between antennas located on a circular cylinder. The design problem of the structure consists of providing the necessary rate of the electromagnetic field attenuation along the structure as compa...

Antenna Electrical downtilt is widely used in mobile communication networks for changing antenna radiation pattern and coverage area when downtilt angle is changed, thus the main lobe of the pattern is tilted which had a large impact on system performance. In this paper, the impact of the mobile electrical antenna downtilt in two locations of Erbil...

Small mechanical strain perturbations are considered in calculations of the poly(G)-poly(C) DNA molecular electronic structure, using a tight-binding framework in conjunction with the theories of Slater-Koster and linear elasticity. Results reveal a strain-induced band gap for DNA which is linearly dependent on the induced strain. Local density of...

We utilize a two-dimensional four-channel DNA model, with a tight-binding (TB) Hamiltonian, and investigate the temperature and the magnetic field dependence of the transport behavior of a short DNA molecule. Random variation of the hopping integrals due to the thermal structural disorder, which partially destroy phase coherence of electrons and re...

A theoretical framework is developed in which elementary particles have a component of their wave function extending into higher spatial dimensions, based on an extension of the Schr"odinger equation to include 4^th and 5^th spatial components [E. R. Hedin, Physics Essays 25, 2 (2012)]. A higher-dimensional harmonic oscillator confining potential l...

Molecular electronics of a double stranded poly(G)-poly(C) DNA molecule under axial mechanical strain is examined with a tight binding scheme. Slater-Koster theory is implemented to describe electronic coupling constants in terms of inter-orbital distances. Electronic structure of an infinite-length DNA model, including band structure and total den...

Multiple, series-coupled nanoscale Aharonov-Bohm rings with a quantum dot (QD) embedded in each arm are analyzed for their transmission and current-voltage (I-V) characteristics. A tight-binding model is used to obtain the electron transmission as a function of energy. Application of an external magnetic field is shown to produce spin-polarized tra...

An advanced two-dimensional tight-binding model including the next nearest-neighbor effects for quantum mechanical electron transport through double-stranded DNA molecules is proposed. Considering the next nearest-neighbor hopping strengths between sites gives a more rational and realistic model for the electron path-way through DNA molecules. We s...

A rigorous solution to the problem of coupling reduction between the receiving and transmitting aperture antennas by using an electromagnetic band gap (EBG) structure is theoretically and experimentally investigated. The estimation of the decoupling level for the synthesised EBG structure is given. The radiation patterns of both the antennas are al...

In this paper, a basic theoretical framework is developed in which elementary particles have a component of their wave function extending into higher spatial dimensions. This model postulates an extension of the Schrödinger equation to include a 4th and 5th spatial component. A higher-dimensional simple harmonic oscillator confining potential local...

This research deals with molecular electronics of DNA double helices. We consider a 10 base-pair poly(G)-poly(C) double stranded DNA molecule, tilted with respect to the intercontact electric field direction. An advanced tight-binding (TB) model including hopping integrals of the next nearest neighbors (NNN) and DNA helix conformation is implemente...

A nanoscale ring structure, typically referred to as an Aharonov-Bohm (AB) ring, with a quantum dot (QD) embedded in each arm serves a unit cell in a chain-like structure. The transmission through the device is presented as a function of the number of rings in the chain. Zeeman-splitting of the QD energy levels is also modeled and its effects are a...

We study theoretically the transport properties through the quasi-one-dimensional (Q1D) one-channel DNA model and two-dimensional (2D) four-channel DNA model. We use a tight-binding (TB) technique to investigate the transmission, current-voltage characteristics, the differential conductance, and localization length as a function of incoming electro...

Two co-planar Aharonov-Bohm (AB) rings with a quantum dot (QD) embedded in each arm are coupled together in series. The energy levels of the four QD's are Zeeman-split by means of an external magnetic field applied parallel to the plane of the rings, introducing up to 8 transmission resonances, including Fano-type resonances. The tight-binding form...

An Aharonov-Bohm (AB) ring with embedded quantum dots (QD) in each arm and one -dimensional nanowires attached as leads acts as a primitive cell in this analysis. When a tunable, external magnetic field is parallel to the surface area of the ring it causes Zeeman splitting in the energy levels of the QDs. An electron that traverses these energy lev...

In this research, an updated tight binding model including nearest-neighbor inter-strand hopping (NIH) strengths for quantum mechanical electron transport through double-stranded DNA molecules is proposed. The motivation for including these additional couplings is their similar hopping mechanism for electron tunneling in computations of DNA electro...

Using the tight-binding formalism, a simplified model of the DNA molecule is analyzed and electron transmission plots as a function of molecular parameters are presented. In addition the Aharonov-Bohm effect is used to study the influence of an external magnetic field on electron transport through the modeled DNA Molecule. Data on the minimum flux...

There exist numerous selection sequence techniques for creating a coupling integral matrix for the calculation of transmission of an electron through a DNA molecule. However, these techniques typically create a matrix which requires a significant amount of computer time and memory, especially for large DNA models. Presented here is a novel techniqu...

We study spin-dependent transport and spin polarization through two asymmetric quantum dots (QD’s) embedded in the arms of an Aharonov-Bohm (AB) ring, in which spin splitting produced by external magnetic fields is incorporated into a tight-binding model Hamiltonian. This device shows a sensitive spin-polarization effect by manipulating either in-p...

A mesoscale Aharonov–Bohm (AB) ring with a quantum dot (QD) embedded in each arm is computationally modeled for unique transmission properties arising from a combination of AB effects and Zeeman splitting of the QD energy levels. A tight-binding Hamiltonian is solved, providing analytical expressions for the transmission as a function of system par...

This paper provides a solution for the design optimization of two-dimensional impedance structures for a given electromagnetic field distribution. These structures must provide electromagnetic compatibility between antennas located on a plane. The optimization problem is solved for a given attenuation of the complete field. Since the design optimiz...

Spintronics is an emerging field in which the spin of the electron is used for switching purposes and to communicate information. In order to obtain spin-polarized electron transmission, the Zeeman effect is employed to produce spin-split energy states in quantum dots which are embedded in the arms of a mesoscopic Aharonov-Bohm (AB) ring heterostru...

Stimulated by intriguing experiments of electrical charge transport through single DNA molecules which are trapped between two metal electrodes [1, 2], we investigate quantum mechanical electron transport along the long axis of the DNA molecule with five poly (dG) and poly (dC) base pairs. Using a quasi-one-dimensional tight-binding model, we calcu...

The temperature dependence of the conductivity of lambda phage DNA has been measured by Tran et al [1] experimentally, where the conductivity displayed strong (weak) temperature dependence above (below) a threshold temperature. In order to understand the temperature effects of electron transport theoretically, we study a two-dimensional and four-ch...

A mesoscale Aharonov-Bohm (AB) ring with a quantum dot (QD) embedded in each arm is studied with a tight-binding model for unique transmission properties arising from a combination of AB effects and Zeeman splitting of the QD energy levels. Theoretical analysis of this system has shown that resonance sharpening of the AB oscillation peaks occurs in...

A mesoscopic Aharonov-Bohm (AB) ring with a quantum dot (QD) embedded in each arm is investigated analytically to provide electron transmission characteristics. A parallel magnetic field provides Zeeman splitting of the QD energy levels. Combined Zeeman energy level splitting and AB-effects occur with a perpendicular field. The contour plots of the...

The transmission and phase properties of electron transport through a quantum dot (QD) with variable coupling to a third-terminal probe are investigated analytically for the case of the QD connected directly to source and drain reservoirs and when the QD is embedded in one arm of an Aharonov-Bohm (AB) ring. Using the tight-binding model, explicit a...

Definition of the SubjectResonance phenomena are a major subject of theoretical and experimentalinvestigations, and the concept of resonances is ubiquitous in physics. The search for new effects related to wave interference and different kinds ofresonances in various physical systems continues to be of interest. Interference of a localized wave wit...

Recently, much interest has arisen in the process of charge transport through DNA due to its fundamental roles in biological processes and in possible novel molecular electronics. We investigate quantum mechanical electron transmission along the long axis of the DNA molecule using a one-dimensional tight-binding model. In this system, we consider a...

We present novel resonant phenomena through parallel non-coupled double quantum dots (QDs) embedded in each arm of an Aharonov–Bohm (AB) ring with magnetic flux passing through its center. The electron transmission through this AB ring with each QD formed by two short-range potential barriers is calculated using a scattering matrix at each junction...

In a balanced Aharonov-Bohm ring with an identical quantum dot (QD) in each arm, the transmission amplitude near resonance consists of a zero and pole which can be made to nearly or exactly overlap in the complex-energy plane. This presents a sensitively balanced region of parameter space in which arbitrarily sharp transmission resonance spikes man...

We study a four-terminal AB-ring with three embedded quantum dots in one arm. A tight-binding model is employed to analytically obtain the transmission through the system. Results show that the magnitude and sharpness of the resonance phase-jumps diminish as a function of the degree of coupling to the extra terminals. The Fano resonance zeros becom...

A three-terminal Aharonov-Bohm ring with a quantum dot embedded in one arm is investigated using the exactly solvable formalism of the tight-binding model. We show that by tuning the degree of coupling to the third terminal, the zero of the Fano resonance in the transmission moves off the real-energy axis and the phase jump of π at the resonance di...

We analyze the novel quantum transmission through parallel-coupled double quantum dots (QD) in an Aharonov-Bohm (AB) ring by employing an exactly solvable tight-binding formalism. Contour plots of the transmission as a function of energy levels in the dots, which can be controlled by applied gate voltages [1], are shown for different inter-dot coup...

In a balanced AB ring with an identical QD in each arm, a combination of Breit-Wigner and Fano resonances presents a sensitively balanced region of parameter space in which arbitrarily sharp transmission resonance spikes manifest. The transmission becomes a resonance zero when the electron Fermi energy matches the quasi-bound state energy of the ma...

Stimulated by recent intriguing experiments with a parallel-coupled double quantum dot (QD) [1] and coupled QD's embedded in an Aharonov-Bohm (AB) ring [2], we investigate the electron tunneling conductance and resonance structure in the presence of inter-dot tunnel coupling of double QD's. First, when direct interaction (either Coulomb repulsion o...

Experimental studies of a toroidal, high-beta plasma discharge with a noncircular cross-section are described. In Extrap T1, four toroidal, current-carrying rings outside the plasma discharge current channel produce a separatrix which bounds the plasma. Plasma currents of up to 40 kA are induced, operating with a toroidal field of up to 0.2 T. The...

We examine new effects arising from the collision of two Fano dipoles formed in the transmission of an Aharonov–Bohm ring with strongly-coupled quantum dots. A new quasi-particle is formed, which behaves as a coupled object called a Fano-quadrupole, giving new possibilities for controlling the transmission as a function of flux.

We examine new effects arising from the collision of Fano dipole resonances as affecting the transmission through an Aharonov-Bohm (AB) ring. The behavior of the zeros of the transmission amplitude as a function of magnetic field is investigated for various coupling integrals between quantum dots in the ring. It is shown that the collision of two F...

The electron transmission and phase, and the AB-oscillation phase of a 3-terminal Aharonov-Bohm (AB) ring with a quantum dot (QD) embedded in one arm are investigated using a tight-binding model. It is shown that in a three-terminal interferometer, the zero of the Fano resonance in the transmission moves off the real energy axis in relation to the...

A nanoscale Aharonov–Bohm (AB) ring functioning as an electron wave interferometer is investigated. The total transmission through the ring is calculated as a function of electron energy and threaded magnetic flux for a fixed upper to lower arm length asymmetry ratio. In addition, we model the effects of an asymmetry in the arm transverse widths by...

Stimulated by recent intriguing experiments with a quantum dot in an Aharonov-Bohm (AB) ring, we investigate novel resonant phenomena by studying the total transmission probability of nanoscale AB rings with an embedded scattering center in one arm and a magnetic flux passing through its center. In the AB ring with double coupled-quantum dots (QDs)...

We examine new effects arising from the collision of Fano dipoles seen in the transmission through an Aharonov-Bohm (AB) ring. An exact solvable model is developed in which the effect of coupling between two quantum dots in one arm of the AB ring is studied. A detailed investigation of the collision of Fano dipole resonances and the formation of a...

The main goal of the present work is to investigate novel resonant phenomena which may arise in the AB rings with specially-designed dots. First, we investigate the total transmission probability through the coupled double quantum dots (QDs) embedded in one of the arms of the AB ring with a magnetic flux passing through its center. We calculate the...

Stimulated by recent intriguing experiments with a quantum dot in an Aharonov-Bohm (AB) interferometer [1, 2], we investigate the total transmission probability of nanoscale AB rings with an embedded scattering center (single or double quantum dots) in one arm and a magnetic flux passing through its center. We find a peculiar quantum transport in t...

The results of an experimental study of electro-optic modulators and waveguides based on polymeric materials are presented. Included are the design, fabrication, and testing of integrated Mach–Zehnder modulators, which are based on polymer films that contain a novel, nonlinear electro-optic chromophore. Studies also show the efficacy of photolithog...

The barium bromide monohalide has been studied by using laser resonance methods in the near-infrared and green-blue wavelength regions. The low-lying B 2Σ+ state has been investigated in a time-resolved experiment using a Ti:sapphire laser operating around 900 nm. No influence on the radiative lifetime due to the B 2Σ interaction with the A′2Δ-A 2Π...

In a linear l = 1 stellarator (Phys. Fluids 30, 2885 (1987)) internal probes are used to measure the structure and temporal behavior of the plasma and magnetic field. At lower densities (and higher temperatures) diffuse-profile equilibria are produced that are perturbed by a kapprox. =0 oscillation. At higher densities (and lower temperatures) shar...

A high-beta linear l = 1 stellarator plasma is produced in a low-compression 3 m theta pinch whose compression coil (22 cm i.d.) is modified to have a helical offset of 2 cm and an axial helical period of 40 cm. Internal probes are used to determine the spatial structure and temporal behavior of the magnetic fields, plasma pressure, and current. Th...

A high-beta linear l = 1 stellarator plasma is produced in a low-compression 3-m theta pinch (the High-Beta Q Machine) whose compression coils are modified to have a helical offset of 2 cm, and an axial helical period of 40 cm. Detailed internal magnetic-probe measurements, in conjunction with axial interferometry and excluded flux measurements, we...

We investigate quantum mechanical electron transmission along the long axis of the DNA molecule using a tight-binding model. Specifically, we use two different DNA models to study the charge transfer efficiency of synthetic ds-DNA. First, the generic form of a simple one-conduction channel model, called the fishbone model, is used. The sugar-phosph...

We study the coupling problem of two waveguide antennas using the design of a two-dimensional inhomogeneous im-pedance structure with a fixed reflected field. Since this structure enables electromagnetic compatibility between an-tennas located on a plane, the behaviors of the electromagnetic field along the impedance structure are investigated. The...