Supercurrent blockade in Josephson junctions with a Majorana wire
  We study the Josephson effect for a topologically nontrivial superconducting (TS) wire with Majorana fermion end states and tunnel-coupled to s-wave BCS superconducting (S) electrodes. In an S-TS junction, no supercurrent flow is possible under fairly general conditions. For the S-TS-S junction, bulk TS quasiparticles must be accessible to have a Josephson effect. In the noninteracting case, we derive the exact current-phase relation (CPR) and find \pi-periodic behavior with negative critical current for weak tunnel couplings. Charging effects then cause the anomalous CPR $I(\varphi)=I_c \cos\varphi$, where the parity-sensitive critical current I_c provides a signature for Majorana states. 
A. Zazunov, R. Egger
cond-mat.mes-hall cond-mat.supr-con