Multipair DC-Josephson Resonances in a biased all-superconducting Bijunction

TL;DR

This paper investigates a superconducting bijunction with quantum dots, revealing multipair resonances and phase-dependent Andreev reflections, which could enable enhanced control of superconducting transport.

Contribution

It introduces a novel all-superconducting bijunction with quantum dots, demonstrating controllable multipair resonances and phase-dependent effects not previously explored.

Findings

Identification of multipair phase-coherent resonances.

Control of multipair current via quantum dot tuning.

Observation of phase shifts in higher-order resonances.

Abstract

An all-superconducting bijunction consists of a central superconductor contacted to two lateral superconductors, such that non-local crossed Andreev reflection is operating. Then new correlated transport channels for the Cooper pairs appear in addition to those of separated conventional Joseph- son junctions. We study this system in a configuration where the superconductors are connected through gate-controllable quantum dots. Multipair phase-coherent resonances and phase-dependent multiple Andreev reflections are both obtained when the voltages of the lateral superconductors are commensurate, and they add to the usual local dissipative transport due to quasiparticles. The two-pair resonance (quartets) as well as some other higher order multipair resonances are {\pi}-shifted at low voltage. Dot control can be used to dramatically enhance the multipair current when the voltages are resonant with the dot levels.