Berlin 2018 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 102: Topology: Majorana Fermions

TT 102.2: Talk

Thursday, March 15, 2018, 16:15–16:30, A 053

Charge-response of the Majorana toric code — •Fabian Hassler and Ananda Roy — JARA Institute for Quantum Information, RWTH Aachen University, 52056 Aachen, Germany

At zero temperature, a two dimensional lattice of Majorana zero modes on mesoscopic superconducting islands has a topologically ordered toric code phase. Recently, a Landau field theory has been proposed for the system that captures its different phases and the associated phase-transitions. It was shown that with the increase of Josephson tunneling between the islands, a continuous symmetry-breaking 3D-XY transition gets transformed into a discrete symmetry-breaking 3D-Ising transition through a couple of tricritical points and first order transitions. Using the proposed field theory, we analyze the charge-response of the system at the different continuous phase-transitions. We calculate the universal conductivity at the 3D-XY transitions and the change in the superconducting density at the Ising transition using 1/N expansion.