Revealing Josephson vortex dynamics in proximity junctions below critical current

Made of a thin non-superconducting metal (N) sandwiched by two superconductors (S), SNS Josephson junctions enable novel quantum functionalities by mixing up the intrinsic electronic properties of N with the superconducting correlations induced from S by proximity. Electronic properties of these devices are governed by Andreev quasiparticles [1] which are absent in conventional SIS junctions whose insulating barrier (I) between the two S electrodes owns no electronic states. Here we focus on the Josephson vortex (JV) motion inside Nb-Cu-Nb proximity junctions subject to electric currents and magnetic fields. The results of local (Magnetic Force Microscopy) and global (transport) experiments provided simultaneously are compared with our numerical model, revealing the existence of several distinct dynamic regimes of the JV motion. One of them, identified as a fast hysteretic entry/escape below the critical value of Josephson current, is analyzed and suggested for low-dissipative logic and memory elements.Comment: 11 pages, 3 figures, 1 table, 43 reference

Experience Using a Distributed Object Oriented Database for a Daq System

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STUDIES ON SWITCH-BASED EVENT BUILDING SYSTEMS IN RD13

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Adiabatic superconducting cells for ultra-low-power artificial neural networks

We propose the concept of using superconducting quantum interferometers for the implementation of neural network algorithms with extremely low power dissipation. These adiabatic elements are Josephson cells with sigmoid- and Gaussian-like activation functions. We optimize their parameters for application in three-layer perceptron and radial basis function networks

Gap junctions support the sustained phase of hypoxic pulmonary vasoconstriction by facilitating calcium sensitization

AIMS: To determine the role of gap junctions (GJs) in hypoxic pulmonary vasoconstriction (HPV). METHODS AND RESULTS: Studies were performed in rat isolated intrapulmonary arteries (IPAs) mounted on a myograph and in anaesthetized rats. Hypoxia induced a biphasic HPV response in IPAs preconstricted with prostaglandin F(2α) (PGF(2α), 3 µM) or 20 mM K(+). The GJ inhibitors 18β-glycyrrhetinic acid (18β-GA, 30 µM), heptanol (3.5 mM), or 2-aminoethoxydiphenyl borate (2-APB) (75 µM) had little effect on the transient Phase 1 of HPV, but abolished the sustained Phase 2 which is associated with Ca(2+) sensitization. The voltage-dependent Ca(2+) channel blocker diltiazem (10 µM) had no effect on HPV, and did not alter the inhibitory action of 18β-GA. Sustained HPV is enhanced by high glucose (15 mM) via potentiation of Ca(2+) sensitization, in the presence of high glucose 18β-GA still abolished sustained HPV. Simultaneous measurement of tension and intracellular Ca(2+) using Fura PE-3 demonstrated that whilst 18β-GA abolished tension development during sustained HPV, it did not affect the elevation of intracellular Ca(2+). Consistent with this, 18β-GA abolished hypoxia-induced phosphorylation of the Rho kinase target MYPT-1. In anaesthetized rats hypoxia caused a biphasic increase in systolic right ventricular pressure. Treatment with oral 18β-GA (25 mg/kg) abolished the sustained component of the hypoxic pressor response. CONCLUSION: These results imply that GJs are critically involved in the signalling pathways leading to Rho kinase-dependent Ca(2+) sensitization during sustained HPV, but not elevation of intracellular Ca(2+), and may explain the dependence of the former on an intact endothelium

Magnetic reversal dynamics of a quantum system on a picosecond timescale

We present our approach for a consistent, fully quantum mechanical description of the magnetization reversal process in natural and artificial atomic systems by means of short magnetic pulses. In terms of the simplest model of a two-level system with a magnetic moment, we analyze the possibility of a fast magnetization reversal on the picosecond timescale induced by oscillating or short unipolar magnetic pulses. We demonstrate the possibility of selective magnetization reversal of a superconducting flux qubit using a single flux quantum-based pulse and suggest a promising, rapid Λ-scheme for resonant implementation of this process. In addition, the magnetization reversal treatment is fulfilled within the framework of the macroscopic theory of the magnetic moment, which allows for the comparison and explanation of the quantum and classical behavior

High linearity SQIF-like josephson-junction structures

Abstract-Recently we reported design approaches for the synthesis of multi-SQUID structures capable of providing high linearity voltage response. These structures were developed to form periodic voltage responses. This paper presents possible design solutions for multi-element structures providing SQIF-like high linearity voltage response. The approach is based on the use of a differential scheme of two parallel SQIFs with arrays oppositely frustrated by applied magnetic field . The differential scheme enables a high efficiency synthesis of highly linear SQIF response by subtraction of deviations from linear law