Conductance matrix symmetries of multiterminal semiconductor-superconductor devices

Nonlocal tunneling spectroscopy of multiterminal semiconductor-superconductor hybrid devices is a powerful tool to investigate the Andreev bound states below the parent superconducting gap. We examine how to exploit both microscopic and geometrical symmetries of the system to extract information on the normal and Andreev transmission probabilities from the multiterminal electric or thermoelectric differential conductance matrix under the assumption of an electrostatic potential landscape independent of the bias voltages, as well as the absence of leakage currents. These assumptions lead to several symmetry relations on the conductance matrix. Next, by considering a numerical model of a proximitized semiconductor wire with spin-orbit coupling and two normal contacts at its ends, we show how such symmetries can be used to identify the direction and relative strength of Rashba versus Dresselhaus spin-orbit coupling. Finally, we study how a voltage-bias-dependent electrostatic potential as well as quasiparticle leakage breaks the derived symmetry relations and investigate characteristic signatures of these two effects.

Automated summary

This paper presents a method for investigating Andreev bound states using nonlocal tunneling spectroscopy of semiconductor-superconductor hybrid devices. By exploiting microscopic and geometrical symmetries, information on transmission probabilities can be extracted from the conductance matrix. A numerical model is used to identify the direction and strength of spin-orbit coupling, and the effects of voltage bias and quasiparticle leakage on symmetry relations are investigated.