Prospects for detecting Majorana fermions

Henrik Schou Røising, University of Oxford

Weekly Theory Seminar.

Abstract. In superconductors with p-wave paired electrons Majorana fermions can appear as localized excitations of zero energy. Such quasiparticles constitute perhaps the simplest example of non-Abelian anyons and have applications in topological quantum computation. As intrinsic p-wave superconductors are rare in nature ingenious suggestions of how to probe superconductivity with similar properties on topological insulator surfaces have been proposed [L. Fu & C. Kane, PRL 100, 096407 (2008)]. In this talk we first focus on one such system, a Majorana beam-splitter interferometer, proposed by Fu & Kane to detect chiral Majorana fermions. We show that vortex-edge coupling and surface-bulk scattering put stringent size limits on such a device in a range of materials, encouraging the search for more highly insulating bulk topological insulators. In the second half of the talk we study the effect of finite temperature in a system of two vortex-bound Majorana fermions of finite separation, finding that thermally exciting vortex core states leads to an algebraic decay in temperature in the energy contrast between the fermion parity ground states. Finite temperature is commonly believed to be among the main roadblocks to exploiting Majorana fermions, a belief our results challenge in light of the recently discovered candidate topological superconductor (LiFe)OHFeSe.

(The slides will be available here)

Published Mar. 6, 2019 5:32 PM - Last modified Mar. 6, 2019 5:32 PM