  A spatially oscillating pair potential $\Delta(r)=\Delta_0 e^{i K\cdot x}$
with momentum $K>\Delta_0/\hbar v$ drives a deconfinement transition of the
Majorana bound states in the vortex cores of a Fu-Kane heterostructure (a 3D
topological insulator with Fermi velocity $v$, on a superconducting substrate
with gap $\Delta_0$, in a perpendicular magnetic field). In the deconfined
phase at zero chemical potential the Majorana fermions form a dispersionless
Landau level, protected by chiral symmetry against broadening due to vortex
scattering. The coherent superposition of electrons and holes in the Majorana
Landau level is detectable as a local density of states oscillation with wave
vector $\sqrt{K^2-(\Delta_0/\hbar v)^2}$. The striped pattern also provides a
means to measure the chirality of the Majorana fermions.
