1301.4408 (Pablo San-Jose et al.)

Multiple Andreev reflection and critical current across a topological
transition in superconducting nanowire junctions    [PDF]

Pablo San-Jose, Jorge Cayao, Elsa Prada, Ramón Aguado

We study transport in biased Josephson junctions made of nanowires with strong spin-orbit coupling, as it transitions into a topological superconducting phase for increasing Zeeman field B. Despite the absence of a fractional steady-state ac Josephson current in the topological phase, the dissipative Multiple Andreev Reflection current I_dc at different junction transparencies is particularly revealing. It exhibits unique features related to topology, such as the gap inversion, the formation of Majorana bound states, and fermion-parity conservation. In contrast, and rather surprisingly, the critical current I_c does not vanish at the critical point where the superconducting gap vanishes, exhibiting a discontinuous dI_c/dB instead. These results demonstrate the feasibility to probe the formation of Majorana states without the need of phase sensitive or noise-related measurements.

View original: http://arxiv.org/abs/1301.4408