Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 102: Topology: Majorana Fermions
TT 102.4: Vortrag
Donnerstag, 15. März 2018, 16:45–17:00, A 053
Majorana bound states in semiconducting carbon nanotubes - Part I (numerics) — •Magdalena Marganska1, Lars Milz1, Wataru Izumida1,2, Christoph Strunk3, and Milena Grifoni1 — 1Institute of Theoretical Physics, University of Regensburg, 93 053 Regensburg, Germany — 2Department of Physics, Tohoku University, Sendai 980 8578, Japan — 3Institute of Experimental and Applied Physics, University of Regensburg, 93 053 Regensburg, Germany
Considering the eminent usefulness which the Majorana states have for the field of quantum computing, their practical realization is eagerly awaited. The two best solid state candidates for Majorana hosts are the proximitized iron chains and proximitized semiconducting nanowires with spin-orbit coupling. The system which we investigate is a proximitized carbon nanotube, where the Majorana bound states arise through a physical mechanism similar as in the nanowire. The nanotube has however several advantages. First, it can be grown with minimal disorder. Second, due to its small size, it can be simulated numerically at the microscopic level. Finally, its tiny diameter reduces the number of relevant transverse modes to exactly one, with spin and valley degeneracy. We present here the results of numerical simulations of a proximitized nanotube, capturing the topological phase transition and the formation of Majorana states at the nanotube ends. We construct an effective analytical four-band model which allows us to analyze the system's symmetries and calculate a topological phase diagram, predicting the parameter ranges of chemical potential and magnetic field which hold the greatest promise for planned experiments.