  We show that the probability of electric field induced interband tunneling in
solid state systems is generically a non-monotonic (oscillatory) function of
the applied field. This unexpected behavior can be understood as arising due to
a common path interference between two distinct tunneling solutions. The
phenomenon is insensitive to magnetic field, and arises whenever the low energy
dispersion relation contains higher order terms in addition to the usual $p^2$
term. Such higher order terms are generically present, albeit with small
co-efficient, so that the oscillatory Zener tunneling is a universal
phenomenon. However, the first `Zener oscillation' occurs at a transmission
probability which is exponentially small when the co-efficient of the higher
order terms is small. This explains why this oscillatory aspect of Zener
tunneling has been hitherto overlooked, despite its universality. The common
path interference is also destroyed by the presence of odd powers of $p$ in the
low energy dispersion relation. Since odd powers of $p$ are strictly absent
only when the tunneling barrier lies along an axis of mirror symmetry, it
follows that the robustness of the oscillatory behavior depends on the
orientation of the tunneling barrier. Bilayer graphene is identified as a
particularly good material for observation of common path interference, due to
its unusual nearly isotropic dispersion relation, where the $p^4$ term makes
the leading contribution.
