Calculation of Electron Transport in Branched Semiconductor Nanostructures Using Quantum Network Model

Electron transport in branched semiconductor nanostructures provides many possibilities for creating fundamentally new devices. We solve the problem of its calculation using a quantum network model. The proposed scheme consists of three computational parts: S-matrix of the network junction, S-matrix of the network in terms of its junctions’ S-matrices, electric currents through the network based on its S-matrix. To calculate the S-matrix of the network junction, we propose scattering boundary conditions in a clear integro-differential form. As an alternative, we also consider the Dirichlet-to-Neumann and Neumannto- Dirichlet map methods. To calculate the S-matrix of the network in terms of its junctions’ S-matrices, we obtain a network combining formula. We find electrical currents through the network in the framework of the Landauer– B¨uttiker formalism. Everywhere for calculations, we use extended scattering matrices, which allows taking into account correctly the contribution of tunnel effects between junctions. We demonstrate the proposed calculation scheme by modeling nanostructure based on two-dimensional electron gas. For this purpose we offer a model of a network formed by smooth junctions with one, two and three adjacent branches. We calculate the electrical properties of such a network (by the example of GaAs), formed by four junctions, depending on the temperature.

THE PARITY GATE: FROM QUANTUM NETWORKS TO ENTANGLEMENT GENERATION

It has been shown recently that parity measurement is an efficient entangler for fermions and hence is a universal resource for fermionic quantum computing with linear elements. In this article, we investigate several properties of the parity P-gate. We construct a simple quantum network model for the P-gate and derive gate identities for it. Finally, we examine entanglement generation using parity measurements.

QUANTUM NETWORK SIMULATIONS OF HIGH Tc CERAMIC SUPERCONDUCTORS

Microwave absorption measurements of the high T c ceramic superconductors reveal reproducible features in weak magnetic fields. These features are qualitatively explained by a quantum network model of these superconducting oxides. The ceramic superconductors are modeled as a set of one-dimensional wires weakly coupled at random nodes. The magnetoconductance, magnetization and susceptibility are computed from the network S-matrix.