Negative conductances of Josephson junctions: Voltage fluctuations and energetics

TL;DR

This paper investigates the voltage fluctuations, transport quality, and energy transduction efficiency of a driven Josephson junction, revealing conditions for negative conductance phenomena and optimal operation regimes.

Contribution

It provides a comprehensive analysis of negative conductance and energy efficiency in Josephson junctions under combined periodic and constant driving currents.

Findings

Identification of parameter regimes with negative conductance

Analysis of voltage fluctuations and transport quality

Conditions for optimal energy transduction

Abstract

We study a resistively and capacitively shunted Josephson junction, which is driven by a combination of time-periodic and constant currents. Our investigations concern three main problems: (A) The voltage fluctuations across the junction; (B) The quality of transport expressed in terms of the P\'eclet number; (C) The efficiency of energy transduction from external currents. These issues are discussed in different parameter regimes that lead to: (i) absolute negative conductance; (ii) negative differential conductance, and (iii) normal, Ohmic-like conductance. Conditions for optimal operation of the system are studied.