  Topological Majorana fermion (MF) quasiparticles have been recently suggested
to exist in semiconductor quantum wires with proximity induced
superconductivity and a Zeeman field. Although the experimentally observed zero
bias tunneling peak and a fractional ac-Josephson effect can be taken as
necessary signatures of MFs, neither of them constitutes a sufficient "smoking
gun" experiment. Since one pair of Majorana fermions share a single
conventional fermionic degree of freedom, MFs are in a sense fractionalized
excitations. Based on this fractionalization we propose a tunneling experiment
that furnishes a nearly unique signature of end state MFs in semiconductor
quantum wires. In particular, we show that a "teleportation"-like experiment is
not enough to distinguish MFs from pairs of MFs, which are equivalent to
conventional zero energy states, but our proposed tunneling experiment, in
principle, can make this distinction.
