Scattering Theory for Quantum Hall Anyons in a Saddle Point Potential

We study the theory of scattering of two anyons in the presence of a quadratic saddle-point potential and a perpendicular magnetic field. The scattering problem decouples in the centre-of-mass and the relative coordinates. The scattering theory for the relative coordinate encodes the effects of anyon statistics in the two-particle scattering. This is fully characterized by two energy-dependent scattering phase shifts. We develop a method to solve this scattering problem numerically, using a generalized lowest Landau level approximation.Comment: 5 pages. Published version, with clarified presentatio

Spectroscopic properties of large open quantum-chaotic cavities with and without separated time scales

The spectroscopic properties of an open large Bunimovich cavity are studied numerically in the framework of the effective Hamiltonian formalism. The cavity is opened by attaching leads to it in four different ways. In some cases, short-lived and long-lived resonance states coexist. The short-lived states cause traveling waves in the transmission while the long-lived ones generate superposed fluctuations. The traveling waves oscillate as a function of energy. They are not localized in the interior of the large chaotic cavity. In other cases, the transmission takes place via standing waves with an intensity that closely follows the profile of the resonances. In all considered cases, the phase rigidity fluctuates with energy. It is mostly near to its maximum value and agrees well with the theoretical value for the two-channel case. As shown in the foregoing paper \cite{1}, all cases are described well by the Poisson kernel when the calculation is restricted to an energy region in which the average $S$ matrix is (nearly) constant.Comment: 13 pages, 4 figure

Effect of gas flow on electronic transport in a DNA-decorated carbon nanotube

We calculate the two-time current correlation function using the experimental data of the current-time characteristics of the Gas-DNA-decorated carbon nanotube field effect transistor. The pattern of the correlation function is a measure of the sensitivity and selectivity of the sensors and suggest that these gas flow sensors may also be used as DNA sequence detectors. The system is modelled by a one-dimensional tight-binding Hamiltonian and we present analytical calculations of quantum electronic transport for the system using the time-dependent nonequilibrium Green's function formalism and the adiabatic expansion. The zeroth and first order contributions to the current $I^{(0)}(\bar{t})$ and $I^{(1)}(\bar{t})$ are calculated, where $I^{(0)} (\bar{t})$ is the Landauer formula. The formula for the time-dependent current is then used to compare the theoretical results with the experiment.Comment: 14 pages, 5 figures and 2 table

Correlated behavior of conductance and phase rigidity in the transition from the weak-coupling to the strong-coupling regime

We study the transmission through different small systems as a function of the coupling strength $v$ to the two attached leads. The leads are identical with only one propagating mode $\xi^E_C$ in each of them. Besides the conductance $G$, we calculate the phase rigidity $\rho$ of the scattering wave function $\Psi^E_C$ in the interior of the system. Most interesting results are obtained in the regime of strongly overlapping resonance states where the crossover from staying to traveling modes takes place. The crossover is characterized by collective effects. Here, the conductance is plateau-like enhanced in some energy regions of finite length while corridors with zero transmission (total reflection) appear in other energy regions. This transmission picture depends only weakly on the spectrum of the closed system. It is caused by the alignment of some resonance states of the system with the propagating modes $\xi^E_C$ in the leads. The alignment of resonance states takes place stepwise by resonance trapping, i.e. it is accompanied by the decoupling of other resonance states from the continuum of propagating modes. This process is quantitatively described by the phase rigidity $\rho$ of the scattering wave function. Averaged over energy in the considered energy window, $$ is correlated with $1-$. In the regime of strong coupling, only two short-lived resonance states survive each aligned with one of the channel wave functions $\xi^E_C$. They may be identified with traveling modes through the system. The remaining $M-2$ trapped narrow resonance states are well separated from one another.Comment: Resonance trapping mechanism explained in the captions of Figs. 7 to 11. Recent papers added in the list of reference

Quantum transport through molecular wires

We explore electron transport properties in molecular wires made of heterocyclic molecules (pyrrole, furan and thiophene) by using the Green's function technique. Parametric calculations are given based on the tight-binding model to describe the electron transport in these wires. It is observed that the transport properties are significantly influenced by (a) the heteroatoms in the heterocyclic molecules and (b) the molecule-to-electrodes coupling strength. Conductance ($g$) shows sharp resonance peaks associated with the molecular energy levels in the limit of weak molecular coupling, while they get broadened in the strong molecular coupling limit. These resonances get shifted with the change of the heteroatoms in these heterocyclic molecules. All the essential features of the electron transfer through these molecular wires become much more clearly visible from the study of our current-voltage ($I$-$V$) characteristics, and they provide several key informations in the study of molecular transport.Comment: 8 pages, 4 figure

Effect of hydrogen adsorption on the quasiparticle spectra of graphene

We use the non-interacting tight-binding model to study the effect of isolated hydrogen adsorbates on the quasiparticle spectra of single-layer graphene. Using the Green's function approach, we obtain analytic expressions for the local density of states and the spectral function of hydrogen-doped graphene, which are also numerically evaluated and plotted. Our results are relevant for the interpretation of scanning tunneling microscopy and angle-resolved photoemission spectroscopy data of functionalized graphene.Comment: 4 pages, 3 figures, minor corrections to tex

Single-particle and Interaction Effects on the Cohesion and Transport and Magnetic Properties of Metal Nanowires at Finite Voltages

The single-particle and interaction effects on the cohesion, electronic transport, and some magnetic properties of metallic nanocylinders have been studied at finite voltages by using a generalized mean-field electron model. The electron-electron interactions are treated in the self-consistent Hartree approximation. Our results show the single-particle effect is dominant in the cohesive force, while the nonzero magnetoconductance and magnetotension coefficients are attributed to the interaction effect. Both single-particle and interaction effects are important to the differential conductance and magnetic susceptibility.Comment: 5 pages, 6 figure