Coherent transport properties of a three-terminal hybrid superconducting interferometer

TL;DR

This paper provides a comprehensive theoretical analysis of a double-loop Josephson interferometer, called $oldsymbol{ extomega}$-SQUIPT, exploring its electronic states, current behaviors, and potential for magnetic sensing applications.

Contribution

It offers a detailed theoretical framework for the $oldsymbol{ extomega}$-SQUIPT, including state transitions, current responses, and transport properties, advancing understanding of multi-terminal superconducting devices.

Findings

Flux tuning induces gapped to gapless transitions.

Josephson currents depend on magnetic fluxes and interface transparency.

The device shows potential for sensitive magnetometry.

Abstract

We present an exhaustive theoretical analysis of a double-loop Josephson proximity interferometer, as the one recently realized by Strambini et al. for the control of the Andreev spectrum via an external magnetic field. This system, called $\omega$-SQUIPT, consists of a T-shaped diffusive normal metal (N) attached to three superconductors (S) forming a double loop configuration. By using the quasiclassical Green function formalism, we calculate the local normalized density of states, the Josephson currents through the device and the dependence of the former on the length of the junction arms, the applied magnetic field and the S/N interface transparencies. We show that by tuning the fluxes through the double loop, the system undergoes transitions from a gapped to a gapless state. We also evaluate the Josephson currents flowing in the different arms as a function of magnetic fluxes and explore the quasi-particle transport, by considering a metallic probe tunnel-coupled to the Josephson junction and calculating its I-V characteristics. Finally, we study the performances of the $\omega$-SQUIPT and its potential applications, by investigating its electrical and magnetometric properties.