2017/05/22 by Christopher J. Pedder, Tobias Meng, Rakesh Tiwari +1
Physics and Astronomy · #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.96.165429
published as Phys. Rev. B 96, 165429 (2017) · 9 pages, 5 figures. A new submission extending and expanding our analysis in arXiv:1507.08881. (v2) References added
arxiv created 2017/05/22 · arxiv updated 2017/10/25
Two-particle backscattering in time-reversal invariant interacting helical electron systems can lead to the formation of quasiparticles with charge e/2. We propose a way to detect such states by means of the Josephson effect in the presence of proximity-induced superconductivity. In this case, the existence of e/2 charges leads to an 8 π-periodic component of the Josephson current which can be identified through measurement of Shapiro steps in Josephson junctions. In particular, we show that even when there is weak explicit time-reversal symmetry breaking, which causes the two-particle backscattering to be a sub-leading effect at low energies, its presence can still be detected in driven, current-biased Shapiro step measurements. The disappearance of some of these steps as a function of the drive frequency is directly related to the existence of non-Abelian zero-energy states. We suggest that this effect can be measured in current state-of-the-art Rashba wires.