  Topological superconductors are gapped superconductors with protected
Majorana surface/edge states on the boundary. In this paper, we study the
Josephson coupling between time-reversal invariant topological superconductors
and s-wave superconductors. The Majorana edge/surface states of time-reversal
invariant topological superconductors in all physical dimensions 1, 2, 3 have a
generic topological property which we named as time-reversal anomaly. Due to
the time-reversal anomaly, the Josephson coupling prefers a nonzero phase
difference between topological and trivial superconductors. The nontrivial
Josesphon coupling leads to a current-flux relation with a half period in a
SQUID geometry, and also a half period Fraunhofer effect in dimension higher
than one. We also show that an in-plane magnetic field restores the ordinary
Josephson coupling, as a sharp signature that the proposed effect is a
consequence of the unique time-reversal property of the topological
edge/surface states. Our proposal provides a general approach to experimentally
verify whether a superconductor is topological or not.
