Qubits from tight knots, bent nano-bars and nano-tubes

We propose a novel mechanism for creating a qubit based on a tight trefoil knot, that is an electron nano-waveguide system so small as to be quantum coherent with respect to curvature-induced effects. To establish tight trefoil knots as legitimate candidates for qubits, we propose an effective curvature-induced potential that produces the two-level system and identify the tunnel coupling between the two local states. The proposed two-level system is geometrical in nature and is macroscopic of origin. It also represents new and peculiar property of the trefoil knot. We also propose a different realization of a qubit based on twisted nano-bars and nano-tubes.