The apparent splitting of zero-bias conductance peaks, apparently observed in
recent experiments concerning Majorana fermions in nanowires coupled to
superconductors, can be interpreted as a manifestation of a transition in the
structure from (massive) Majorana to (massless) Weyl fermions. A modification
of the experiments in order to test such phenomenon is proposed by making
recourse to the only possible electromagnetic interaction allowed to (massive)
Majorana particles and mediated by their anapole moment. In suitably designed
heterostructures with toroidal symmetry, the additional anapole interaction
manifests itself in the lowering of the critical magnetic field required for
the appearance of the zero-bias peak, a shift that can be directly measured and
thus reveal the presence of Majorana (rather than Weyl) fermions. Anapole
interactions, though not previously considered, may also be a powerful method
to control the dynamics of Majorana fermions, and then to manipulate the qubit
state in quantum computationComment: revtex, 6 pages, 2 figures; to be published in Europhysics Letter
