Conductance-matrix symmetries of multiterminal semiconductor-superconductor devices

Abstract

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-biasdependent electrostatic potential as well as quasiparticle leakage break the derived symmetry relations and investigate characteristic signatures of these two contributions.

Nonlocal measurement of quasiparticle charge and energy relaxation in proximitized semiconductor nanowires using quantum dots

“…We further note that although one is tempted to associate the NLC observed in our system directly with the relevant transmission amplitudes expressed here, the scattering formalism itself is insufficient to model some important aspects of the actual transport. The scattering formalism assumes that the motion of the QPs in the system conserves energy [56], but this assumption does not hold in our system since we observe that energy relaxation plays an important role in NLC. We thus conclude that while the presence or absence of NLC can serve as a useful tool in the determination of the induced gap, a quantitative analysis of NLC should go beyond the scattering formalism.…”

Phase Asymmetry of Andreev Spectra From Cooper-Pair Momentum

“…Three-terminal conductance spectroscopy can be used to further probe nonreciprocity of the ABS spectrum. Measurements of the 2×2 matrix of differential conduc- Nonlocal spectra indicate that phase-asymmetric ABSs extend throughout the bulk of the junction, as opposed to localized features associated only with the device ends [43,44]. Extended ABSs mediate nonlocal transport between the two device ends, leading to a finite phaseasymmetric nonlocal conductance signal.…”

Creating and detecting poor man's Majorana bound states in interacting quantum dots

“…However, depending on T relative to the gap to excited states, it can be hard to accurately determine the sweet spot based on a local conductance measurement. It is known that nonlocal conductance, for example G LR = dI L /dV R , can reveal additional information about subgap states [54][55][56][57]. Figures 3(b), (d) and (f) show G LR corresponding to the parameters in Figs.…”