Chiral symmetry breaking and the Josephson current in a ballistic superconductor-quantum wire-superconductor junction

Artikel i vetenskaplig tidskrift, 2004

We evaluate the Josephson current through a quasi-1D quantum wire coupled to bulk superconductors. It Is shown that the interplay of Rashba spin-orbit interaction and Zeeman splitting results in the appearence of a Josephson current even in the absence of any phase difference between the superconductors. In a transparent junction (D [asymptotically equal to] 1) at low temperatures this anomalous supercurrent Jan appears abruptly for a Zeeman splitting of the order of the Andreev level spacing as the magnetic field is varied. In a low transparency (D very much less than 1) junction one has Jan α root D under special (resonance) conditions. In the absence of Zeeman splitting the anomalous supercurrent disappears. We have investigated the influence of dispersion asymmetry induced by the Rashba interaction in quasi-1D quantum wires on the critical Josephson current and have shown that the breakdown of chiral symmetry enhances the supercurrent.