Dresden 2017 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 16: Transport: Topological Phases (jointly with DS, MA, HL, O)
TT 16.4: Talk
Monday, March 20, 2017, 15:45–16:00, HSZ 304
Topological invariants in carbon nanotubes with superconducting pairing — •Lars Milz1, Magdalena Marganska1, Wataru Izumida1,2, and Milena Grifoni1 — 1Institute for Theoretical Physics, University of Regensburg, 93 047 Regensburg, Germany — 2Department of Physics, Tohoku University, Sendai 980-8578, Japan
The symmetries present in a gapped Hamiltonian system determine the types of topological invariants which can be defined for that system. Our case of interest here is a carbon nanotube, which in its normal state is known to possess a non-trivial integer topological invariant, the winding number. Its value determines the number of edge states. When a superconducting pairing is imposed on the nanotube, the symmetry class of the system changes and it is possible to define also a Z2 Pfaffian topological invariant, exploiting the particle-hole rather than the chiral symmetry. We explore the relationship between the two invariants and their influence on the energy spectrum and eigenstates, in particular the edge modes, of a finite carbon nanotube.