  We consider Majorana zero modes in a Josephson junction on top of a
topological insulator in transverse magnetic field. Majorana zero modes reside
at periodically located nodes of Josephson vortices. We find that hybridization
of these modes is prohibited by symmetries of the problem at vanishing chemical
potential, which ensures better protection of zero modes and yields methods to
control the tunnel coupling between Majorana modes for quantum information
processing applications.
