  Majorana fermions can be realized as quasiparticles in topological
superconductors, with potential applications in topological quantum computing.
Recently, lattices of magnetic adatoms deposited on the surface of s-wave
superconductors - Shiba lattices - have been proposed as a new platform for
topological superconductivity. These systems possess the great advantage that
they are accessible via scanning-probe techniques, and thus enable the local
manipulation and detection of Majorana modes. Realizing quantum bits on this
basis will rely on the creation of nanoscopic Shiba lattices, so-called Shiba
islands. Here, we demonstrate that the topological Majorana edge modes of such
islands display universal electronic and transport properties. Most remarkably,
these Majorana modes possess a quantized charge conductance that is
proportional to the topological Chern number, C, and carry a supercurrent whose
chirality reflects the sign of C. These results establish nanoscopic Shiba
islands as promising components in future topology-based devices.
