Transport signatures of inverted Andreev bands in topological Josephson junctions

TL;DR

This paper investigates the unique thermoelectric transport signatures of inverted Andreev bands in topological Josephson junctions with a quantum dot, revealing how band inversion affects conductance and thermoelectric properties.

Contribution

It introduces an effective resonant tunneling model for topological Josephson junctions and analyzes how band inversion influences thermoelectric transport.

Findings

Inverted Andreev bound states occur in p-wave symmetric junctions.

Sign change in the Seebeck coefficient indicates topological band inversion.

Transport coefficients reflect the induced gap and band inversion effects.

Abstract

We study the thermoelectrical transport transverse to conventional and topological Josephson junctions with a central quantum dot (QD). For that purpose, we derive an effective resonant tunneling model where the QD is renormalized with an induced superconducting gap. By applying the Keldysh Green's function technique, we compute the local density of states as well as the transmission functions. In the latter case, we observe that the Andreev bound states forming on the QD are inverted if the junction has $p$-wave symmetry, meaning that electron and hole orbitals switch roles. We calculate the thermoelectric transport coefficients both analytically and numerically and show how the induced gaps and the band inversion are reflected in the electrical and heat conductance as well as the Seebeck coefficient, the latter experiencing a sign change in the topological case.