QUANTUM COMPUTATION WITH MAJORANA FERMIONS IN TOPOLOGICAL SUPERCONDUCTORS

by Bernard van Heck (Leiden Univ.)

Monday 28 May 2012, 16:00 → 17:30 Europe/Rome

Aula Conversi (Dip. di Fisica - Edificio G. Marconi)

Majorana fermions are particles which are equal to their own antiparticles. While they are yet to be found as elementary constituents of nature, they can also emerge as zero-energy midgap states in several condensed matter systems, for instance at the end points of a 1D nanowire deposited on top of a superconductor. Most interestingly, Majorana fermions exhibit non-Abelian braiding statistics and can therefore be used as building blocks for a fault-tolerant quantum computer. I will describe a scheme to realize protected quantum gates manipulating Majorana fermions in a 2D network of superconductors. I will explain how, despite being themselves neutral particles, Majorana fermions are coupled by the charging energy of the underlying superconductor. The coupling can be switched on and off by varying the magnetic flux through a split Josephson junction. This opens the possibility to effectively move and exchange (braid) the Majorana fermions. I will show how to build a universal set of quantum gates out of these protected operations.