Transport signatures of single and multiple Floquet Majorana modes in one-dimensional Rashba nanowire and Shiba chain

TL;DR

This paper theoretically explores how Floquet Majorana modes in Rashba nanowires and Shiba chains influence transport properties, revealing quantized conductance signatures and stability against disorder, with implications for experimental detection.

Contribution

It introduces a comprehensive analysis of transport signatures of single and multiple Floquet Majorana modes in realistic 1D systems, including stability and multiple mode effects.

Findings

Quantized differential conductance of 2e^2/h for single modes.

Sum over photon sectors supports Floquet sum rule.

Quantized conductance proportional to the number of modes.

Abstract

We theoretically investigate the transport signature of single and multiple Floquet Majorana end modes~(FMEMs), appearing in an experimentally feasible setup with Rashba nanowire~(NW) placed in closed proximity to a conventional $s$-wave superconductor, in the presence of an external Zeeman field. Periodic drive causes the anomalous $\pi$-modes to emerge in addition to the regular $0$-modes in the driven system where the former does not exhibit any static analog. For single $0$- and/or $\pi$-FMEM, differential conductance exhibits a quantized value of $2e^{2}/h$ while we consider the sum over all the photon sectors, supporting Floquet sum rule. We examine the stability of this summed conductance against random onsite disorder. We further investigate the summed conductance in several cases hosting multiple~(more than one) $0$- or $\pi$-modes at the end of the NW. In these cases, we obtain quantized values of $n_{M}\times 2e^{2}/h$ in summed differential conductance with $n_{M}$ being the number of modes~($0$ or $\pi$) localized at one end of the NW. We repeat our analysis for another experimentally realizable model system known as helical Shiba chain. Moreover, we corroborate our results by computing the differential conductance for FMEMs using non-equilibrium Green's function method. Our work opens up the possibility of studying the transport signatures of FMEMs in these realistic models.