Zerofrequency supercurrent susceptibility signatures of trivial and topological zeroenergy states in nanowire junctions
Abstract
We propose a method to distinguish between trivial and topological, Majorana, zeroenergy states (ZESs) in both short and long superconductornormalsuperconductor junctions based on Rashba nanowires using phasebiased equilibrium transport measurements. In particular, we show how the sawtooth profile of the supercurrent, due to the Majorana oscillation suppression in the topological phase for sufficiently long superconductor regions, leads to a strong signal in its zerofrequency susceptibility for a phase difference of $\phi = \pi$ . This signal is notably insensitive to the chemical potential in the normal region, while trivial ZESs only causes signals in the susceptibility that is highly varying with the chemical potential, thus turning gating of the normal region into a simple experimental control knob. Furthermore, we obtain that, by tuning the junction transparency, critical currents in both short and long junctions undergo a reduction in the number of oscillations as a function of magnetic field only in the topological phase, an effect that find to be intimately linked to Majorana nonlocality. Finally, we show that our results also hold at finite temperatures, thus highlighting their potential measurability under realistic experimental conditions.
 Publication:

Superconductor Science Technology
 Pub Date:
 March 2023
 DOI:
 10.1088/13616668/acb670
 arXiv:
 arXiv:2209.02094
 Bibcode:
 2023SuScT..36c4003B
 Keywords:

 supercurrents;
 topological superconductivity;
 Majorana bound states;
 trivial zeroenergy states;
 supercurrent susceptibility;
 Josephson effect;
 Condensed Matter  Mesoscale and Nanoscale Physics;
 Condensed Matter  Superconductivity
 EPrint:
 12 pages, 7 figures. Published version