Regensburg 2025 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 53: Topology: Other Topics
TT 53.6: Talk
Friday, March 21, 2025, 10:45–11:00, H32
Topological characterization of carbon nanotubes — •Udo Schwingenschlögl, Xiaoning Zang, and Nirpendra Singh — King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
Orbital angular momentum plays a central role in quantum mechanics, from the microscopic interaction between light and matter to the macroscopic behavior of superconductors and superfluids. We show that the topology of carbon nanotubes can be characterized by winding numbers related to the orbital angular momentum. The tight-binding Hamiltonian of any carbon nanotube with CN symmetry can be represented by N tight-binding Hamiltonians of decoupled molecular chains, for which a pseudospin formulation, characterized by specific paths in a two-dimensional auxiliary space, is developed. The quantum phases are given by the N winding numbers of these paths. The paths rotate in the auxiliary space when a magnetic field of varying strength is applied along the carbon nanotube, which gives rise to quantum phase transitions.