Josephson current and noise at a superconductor/quantumspinHallinsulator/superconductor junction
Abstract
We study junctions between superconductors mediated by the edge states of a quantumspinHall insulator. We show that such junctions exhibit a fractional Josephson effect, in which the current phase relation has a 4π rather than a 2π periodicity. This effect is a consequence of the conservation of fermion parity—the number of electron mod2 —in a superconducting junction and is closely related to the Z_{2} topological structure of the quantumspinHall insulator. Inelastic processes, which violate the conservation of fermion parity, lead to telegraph noise in the equilibrium supercurrent. We predict that the lowfrequency noise due these processes diverges exponentially with temperature T as T→0 . Possible experiments on HgCdTe quantum wells will be discussed.
 Publication:

Physical Review B
 Pub Date:
 April 2009
 DOI:
 10.1103/PhysRevB.79.161408
 arXiv:
 arXiv:0804.4469
 Bibcode:
 2009PhRvB..79p1408F
 Keywords:

 74.78.Fk;
 03.67.Lx;
 71.10.Pm;
 74.45.+c;
 Multilayers superlattices heterostructures;
 Quantum computation;
 Fermions in reduced dimensions;
 Proximity effects;
 Andreev effect;
 SN and SNS junctions;
 Condensed Matter  Mesoscale and Nanoscale Physics;
 Condensed Matter  Superconductivity
 EPrint:
 4 pages, 2 figures