  A junction between two topological superconductors containing a pair of
Majorana fermions exhibits a `fractional' Josephson effect, $4\pi$ periodic in
the superconductors' phase difference. An additional fractional Josephson
effect, however, arises when the Majoranas are spatially separated by a
superconducting barrier. This new term gives rise to a set of Shapiro steps
which are essentially absent without Majorana modes and therefore provides a
unique signature for these exotic states.
