Giant noise-to-current ratio as a signature of dispersing Majorana edge modes

We theoretically study multiterminal transport in a setup consisting of two normal metal leads connected to a topological superconductor hosting one-dimensional dispersing Majorana edge modes. In the proposed system, the unpaired nature of the Majorana edge modes inherently leads to a strong suppression of the charge current in the linear response regime, while the current fluctuations remain significant. As a result, the noise-to-current ratio becomes substantially enhanced at low bias voltages, providing a clear signature of the dispersing Majorana edge modes. We reach this conclusion analytically, without relying on any specific model of topological superconductors. The predicted giant noise-to-current ratio is verified through numerical calculations using tight-binding models of topological-insulator-based topological superconductors. We also discuss the application of our proposal to the ${\mathrm{CoSi}}_{2}/{\mathrm{TiSi}}_{2}$ heterostructure and the iron-based superconductor ${\mathrm{FeTe}}_{1\ensuremath{-}x}{\mathrm{Se}}_{x}$.