The solid-state Ku-band power amplifier

A survey of IMPATT diodes and negative resistance amplifiers is presented. The first phase of the amplifier effort is discussed in which a single diode reflection amplifier delivering 0.5 watt at 15 GHz with 10-dB gain over a 1-GHz band was developed. The design of a dominant mode resonant combiner is described along with the characterization of the IMPATT diodes. Results are given on the complete amplifier and on the thermal and graceful failure characteristics of the unit

Phase-Coherent Transport through a Mesoscopic System: A New Probe of Non-Fermi-Liquid Behavior

A novel chiral interferometer is proposed that allows for a direct measurement of the phase of the transmission coefficient for transport through a variety of mesoscopic structures in a strong magnetic field. The effects of electron-electron interaction on this phase is investigated with the use of finite-size bosonization techniques combined with perturbation theory resummation. New non-Fermi-liquid phenomena are predicted in the FQHE regime that may be used to distinguish experimentally between Luttinger and Fermi liquids.Comment: 4 pages, 3 figures, Revte

Life Cycle Assessment of a Small Hydropower Plant in the Brazilian Amazon

Brazil as well as the rest of the world, faces a major challenge related to the electricity sector, to meet the growing demand with energy production from renewable sources. Many hydroelectric plants are being implemented, especially in the northern region of Brazil, but its environmental impacts are yet unknown. Energy produced by hydropower plants has been considered totally renewable and clean, but more recent studies describe analysis pointing to the existence of emissions by hydroelectric plants, especially if a lifecycle approach is considered. Thus, the objective of this study is the investigation of environmental impacts of the construction, operation and decommissioning of a hydroelectric power station based on life cycle assessment. The main focus is the Curuá-Una hydropower plant that is located in the Amazon forest in northern Brazil, in Santarém municipality (Pará state)

Universal Equilibrium Currents in the Quantum Hall Fluid

The equilibrium current distribution in a quantum Hall fluid that is subjected to a slowly varying confining potential is shown to generally consist of strips or channels of current, which alternate in direction, and which have universal integrated strengths. A measurement of these currents would yield direct independent measurements of the proper quasiparticle and quasihole energies in the fractional quantum Hall states.Comment: 4 pages, Revte

Superconducting Qubits Coupled to Nanoelectromechanical Resonators: An Architecture for Solid-State Quantum Information Processing

We describe the design for a scalable, solid-state quantum-information-processing architecture based on the integration of GHz-frequency nanomechanical resonators with Josephson tunnel junctions, which has the potential for demonstrating a variety of single- and multi-qubit operations critical to quantum computation. The computational qubits are eigenstates of large-area, current-biased Josephson junctions, manipulated and measured using strobed external circuitry. Two or more of these phase qubits are capacitively coupled to a high-quality-factor piezoelectric nanoelectromechanical disk resonator, which forms the backbone of our architecture, and which enables coherent coupling of the qubits. The integrated system is analogous to one or more few-level atoms (the Josephson junction qubits) in an electromagnetic cavity (the nanomechanical resonator). However, unlike existing approaches using atoms in electromagnetic cavities, here we can individually tune the level spacing of the ``atoms'' and control their ``electromagnetic'' interaction strength. We show theoretically that quantum states prepared in a Josephson junction can be passed to the nanomechanical resonator and stored there, and then can be passed back to the original junction or transferred to another with high fidelity. The resonator can also be used to produce maximally entangled Bell states between a pair of Josephson junctions. Many such junction-resonator complexes can assembled in a hub-and-spoke layout, resulting in a large-scale quantum circuit. Our proposed architecture combines desirable features of both solid-state and cavity quantum electrodynamics approaches, and could make quantum information processing possible in a scalable, solid-state environment.Comment: 20 pages, 14 separate low-resolution jpeg figure

Quantum interference and electron-electron interactions at strong spin-orbit coupling in disordered systems

Transport and thermodynamic properties of disordered conductors are considerably modified when the angle through which the electron spin precesses due to spin-orbit interaction (SOI) during the mean free time becomes significant. Cooperon and Diffusion equations are solved for the entire range of strength of SOI. The implications of SOI for the electron-electron interaction and interference effects in various experimental settings are discussed.Comment: 4 pages, REVTEX, 1 eps.figure Submitted to Phys. Rev. Let

Magnus Force in High Temperature Superconductivity and Berry Phase

In the topological framework of high temperature superconductivity we have discussed the Magnus force acting on its vortices