Multi-Terminal Josephson Junctions as a novel platform for high dimensional topological matter

Informations projet

TopoInMulTermJJ

N° de convention de subvention: 753906

DOI

10.3030/753906

Projet clôturé

Date de signature de la CE 27 Mars 2017

Date de début 1 Octobre 2017

Date de fin 30 Septembre 2019

Financé au titre de

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Coût total

€ 173 076,00

Contribution de l’UE

€ 173 076,00

Coordonné par

UNIVERSITE GRENOBLE ALPES
France

Periodic Reporting for period 1 - TopoInMulTermJJ (Multi-Terminal Josephson Junctions as a novel platform for high dimensional topological matter)

Période du rapport: 2017-10-01 au 2019-09-30

Résumé du contexte et des objectifs généraux du projet

Josephson junctions host so-called Andreev bound states. As has been shown recently, the spectrum of Andreev bound states in an N-terminal Josephson junction as function of the superconducting phases can be viewed as a pseudo-bandstructure in N-1 dimension. This pseudo-bandstructure may have interesting topological properties. However, many questions concerning the characterization, classification, and manipulation of the topological states in multi-terminal Josephson junctions are still open. The objective of the project was to further explore this novel platform for topological matter.

Travail effectué depuis le début du projet jusqu’à la fin de la période considérée dans le rapport et principaux résultats atteints jusqu’à présent

In the beginning of the project, general properties of multi-terminal Josephson junctions were investigated. Furthermore, it was shown that coupling two 3-terminal junctions via a common superconducting island makes it impossible to reach the Weyl points that may be present in the Andeev spectrum of a single junction. This rules out one of the original ideas in the proposal.

Subsequently, the effect of Berry curvature on electronic transport was studied. While the appearance of a first Chern number can be seen in the first order perturbation correction to the adiabatic result, here a second order perturbation expansion was performed to explore whether new phenomena appear. The results still have to be applied to a concrete realization that would allow one to interpret them

Progrès au-delà de l’état des connaissances et impact potentiel prévu (y compris l’impact socio-économique et les conséquences sociétales plus larges du projet jusqu’à présent)

The researcher is planning to continue the investigation on the last project after the end of the fellowship. The identification of a measurable quantity probing the higher order terms is expected to stimulate further activity in the research field of topological properties of matter.

Examples of geometric setups of Multi-terminal Josephson junctions