Dynamics of Josephson junctions and single-flux-quantum networks with superconductor-insulator-normal metal junction shunts

TL;DR

This paper models Josephson junctions with SIN junction shunts, revealing how their impedance affects circuit dynamics, damping, and capacitance, and demonstrating their operation in flux-quanta circuits.

Contribution

It introduces a microscopic model for SIN-shunted Josephson junctions, highlighting their unique impedance effects and validating their use in flux-quanta circuits.

Findings

SIN impedance causes frequency-dependent damping and reactance.

Effective capacitance of the circuit increases due to SIN impedance.

Basic flux-quanta circuits operate correctly with SIN-shunted junctions.

Abstract

Within the framework of the microscopic model of tunneling, we modelled the behavior of the Josephson junction shunted by the Superconductor-Insulator-Normal metal (SIN) tunnel junction. We found that the electromagnetic impedance of the SIN junction yields both the frequency-dependent damping and dynamic reactance which leads to an increase in the effective capacitance of the circuit. We calculated the dc I-V curves and transient characteristics of these circuits and explained their quantitative differences to the curves obtained within the resistively shunted junction model. The correct operation of the basic single-flux-quanta circuits with such SIN-shunted junctions, i.e. the Josephson transmission line and the toggle flip-flop, have also been modelled.