Chiral adiabatic transmission protected by Fermi surface topology

TL;DR

This paper reveals that the topological properties of the Fermi surface and superconducting phase differences induce chiral adiabatic transmission in Josephson junctions, which can be observed in conductance and thermal transport experiments.

Contribution

It introduces the concept of chiral adiabatic transmission (CAT) governed by Fermi surface topology and phase vorticity, providing a new understanding of transport in Josephson junctions.

Findings

Perfect transmission occurs at junctions where three meet.

Chirality and number of channels depend on Fermi surface topology.

CAT can be observed in conductance and thermal measurements.

Abstract

We demonstrate that Andreev modes that propagate along a transparent Josephson junction have a perfect transmission at the point where three junctions meet. The chirality and the number of quantized transmission channels is determined by the topology of the Fermi surface and the vorticity of the superconducting phase differences at the trijunction. We explain this chiral adiabatic transmission (CAT) as a consequence of the adiabatic evolution of the scattering modes both in momentum and real space. The dispersion relation of the junction then separates the scattering trajectories by introducing inaccessible regions of phase space. We expect that CAT is observable in nonlocal conductance and thermal transport measurements. Furthermore, because it does not rely on particle-hole symmetry, CAT is also possible to observe directly in metamaterials.