Energy structure, density of states and transmission properties of the periodic 1D Tight-Binding lattice with a generic unit cell of uu sites

We report on the electronic structure, density of states and transmission properties of the periodic one-dimensional Tight-Binding (TB) lattice with a single orbital per site and nearest-neighbor interactions, with a generic unit cell of $u$ sites. The determination of the eigenvalues is equivalent to the diagonalization of a real tridiagonal symmetric $u$-Toeplitz matrix with (cyclic boundaries) or without (fixed boundaries) perturbed upper right and lower left corners. We solve the TB equations via the Transfer Matrix Method, producing, analytical solutions and recursive relations for its eigenvalues, closely related to the Chebyshev polynomials. We examine the density of states and provide relevant analytical relations. We attach semi-infinite leads, determine and discuss the transmission coefficient at zero bias and investigate the peaks number and position, and the effect of the coupling strength and asymmetry as well as of the lead properties on the transmission profiles. We introduce a generic optimal coupling condition and demonstrate its physical meaning.Comment: 23 pages, 20 figure

Evaluation of Compton scattering sequence reconstruction algorithms for a portable position sensitive radioactivity detector based on pixelated Cd(Zn)Te crystals

We present extensive simulation studies on the performance of algorithms for the Compton sequence reconstruction used for the development of a portable spectroscopic instrument (COCAE), with the capability to localize and identify radioactive sources, by exploiting the Compton scattering imaging. Various Compton Sequence reconstruction algorithms have been compared using a large number of simulated events. These algorithms are based on Compton kinematics, as well as on statistical test criteria that exploit the redundant information of events having two or more photon interactions in the active detector's volume. The efficiency of the best performing technique is estimated for a wide range of incident gamma-ray photons emitted from point-like gamma sources.Comment: 16 pages, 17 figure

Electronic structure and carrier transfer in B-DNA monomer polymers and dimer polymers: Stationary and time-dependent aspects of wire model vs. extended ladder model

We employ two Tight-Binding (TB) approaches to study the electronic structure and hole or electron transfer in B-DNA monomer polymers and dimer polymers made up of $N$ monomers (base pairs): (I) at the base-pair level, using the on-site energies of base pairs and the hopping integrals between successive base pairs, i.e., a wire model and (II) at the single-base level, using the on-site energies of the bases and the hopping integrals between neighboring bases, i.e., an \textit{extended} ladder model since we also include diagonal hoppings. We solve a system of $MD$ ("matrix dimension") coupled equations [(I) $MD$ = $N$, (II) $MD$ = $2N$] for the time-independent problem, and a system of $MD$ coupled $1^\text{st}$ order differential equations for the time-dependent problem. We study the HOMO and the LUMO eigenspectra, the occupation probabilities, the Density of States (DOS) and the HOMO-LUMO gap as well as the mean over time probabilities to find the carrier at each site [(I) base pair or (II) base)], the Fourier spectra, which reflect the frequency content of charge transfer (CT) and the pure mean transfer rates from a certain site to another. The two TB approaches give coherent, complementary aspects of electronic properties and charge transfer in B-DNA monomer polymers and dimer polymers.Comment: 20 pages, 23 figure

Coherent control of microwave pulse storage in superconducting circuits

Coherent pulse control for quantum memory is viable in the optical domain but nascent in microwave quantum circuits. We show how to realize coherent storage and on-demand pulse retrieval entirely within a superconducting circuit by exploiting and extending existing electromagnetically induced transparency technology in superconducting quantum circuits. Our scheme employs a linear array of superconducting artificial atoms coupled to a microwave transmission line.Comment: 13 pages, 4 figures and some supplementary materia

Passage-time statistics of superradiant light pulses from Bose-Einstein condensates

We discuss the passage-time statistics of superradiant light pulses generated during the scattering of laser light from an elongated atomic Bose-Einstein condensate. Focusing on the early-stage of the phenomenon, we analyze the corresponding probability distributions and their scaling behaviour with respect to the threshold photon number and the coupling strength. With respect to these parameters, we find quantities which only vary significantly during the transition between the Kapitza Dirac and the Bragg regimes. A possible connection of the present observations to Brownian motion is also discussed.Comment: Close to the version published in J. Phys.

Non-Markovian dynamics in atom-laser outcoupling from a double-well Bose-Einstein condensate

We investigate the dynamics of a continuous atom laser based on the merging of independently formed atomic condensates. In a first attempt to understand the dynamics of the system, we consider two independent elongated Bose-Einstein condensates which approach each other and focus on intermediate inter-trap distances so that a two-mode model is well justified. In the framework of a mean-field theory, we discuss the quasi steady-state population of the traps as well as the energy distribution of the outcoupled atoms.Comment: 21 pages, 9 figure, to appear in J. Phys.