Two coupled Josephson junctions: dc voltage controlled by biharmonic current

TL;DR

This paper investigates how two coupled Josephson junctions can generate and control dc voltages through biharmonic ac currents and external coupling, enabling efficient manipulation of voltages across both junctions.

Contribution

It introduces a model of coupled Josephson junctions driven by biharmonic currents, demonstrating controllable dc voltage generation and manipulation via external shunt resistance.

Findings

Dc voltage can be rectified and controlled in the first junction.

Coupling allows dc voltage generation in the second junction.

Voltages can be switched from positive to negative by parameter variation.

Abstract

We study transport properties of two Josephson junctions coupled by an external shunt resistance. One of the junction (say, the first) is driven by an unbiased ac current consisting of two harmonics. The device can rectify the ac current yielding a dc voltage across the first junction. For some values of coupling strength, controlled by an external shunt resistance, a dc voltage across the second junction can be generated. By variation of system parameters like the relative phase or frequency of two harmonics, one can conveniently manipulate both voltages with high efficiency, e.g., changing the dc voltages across the first and second junctions from positive to negative values and vice versa.