Day 2 Dec-3 2021
Session 4 15:45-16:30



Deconfinement of Majorana vortex modes in a topological superconductor

Carlo Beenakker
beenakker@lorentz.leidenuniv.nl
Lorentz Institute for theoretical physics
Leiden University, The Netherlands

A spatially oscillating pair potential drives a deconfinement transition of the Majorana bound states in the vortex cores of a Fu-Kane heterostructure (a 3D topological insulator on a superconducting substrate, in a perpendicular magnetic field). In the deconfined phase at zero chemical potential the Majorana fermions form a dispersionless Landau level, protected by chiral symmetry against broadening due to vortex scattering. Unlike a conventional electronic Landau level, the Majorana Landau level has a non-uniform density profile: quantum interference of the electron and hole components creates spatial oscillations with a wave vector set by the Cooper pair momentum that drives the deconfinement transition. The striped pattern provides a means to measure the chirality of the Majorana fermions. As an outlook to future investigations, we will discuss the possibility to braid the delocalized Majorana fermions.

Intensity profile of the deconfined phase of a Majorana zero mode in a vortex lattice shows a pronounced periodic modulation in the direction parallel to the Cooper pair momentum, with bifurcation points at the vortex cores.

Reference:

M.J. Pacholski, G. Lemut, O. Ovdat, I. Adagideli, and C.W.J. Beenakker Phys. Rev. Lett. 126, 226801 (2021).


Carlo Beenakker studied physics at Leiden University (Ph.D. 1984). He worked at the Philips Research Laboratories before returning to Leiden in 1991 as professor of theoretical physics at the Lorentz Institute, a chair he holds to this date.

In 1987, while at Philips Research, Carlo Beenakker contributed to the discovery and explanation of conductance quantization in a quantum point contact, for which he shared the Royal Dutch Shell prize (1993). In Leiden he continued his research on quantum transport in nanostructures, honored with the Spinoza prize (1999), which is the highest scientific award in the Netherlands, the Physica prize (2003), and the AKZO Nobel Science Award (2006). His recent research is in the field of topological superconductivity, focusing on the ways in which Majorana fermions can be used for topological quantum computations, in close collaboration with the QuTech laboratory in Delft.

Carlo Beenakker has co-authored over 350 publications and is recognized by the Web of Science as a "Highly-cited Researcher". For his services to science and society he was elected member to the Royal Netherlands Academy of Arts and Sciences and knighted in the Order of the Dutch Lion.