We have studied the tachyonic excitations in the junction of two topological
insulators in the presence of an external magnetic field. The Landau levels,
evaluated from an effective two-dimensional model for tachyons, and from the
junction states of two topological insulators, show some unique properties not
seen in conventional electrons systems or in graphene. The ν=1/3 fractional
quantum Hall effect has also a strong presence in the tachyon system.Comment: 5 pages, 3 figure