Kulik, I. O.2018-04-122018-04-12200597898127016199789812564689http://hdl.handle.net/11693/37824Fixed-number-of-electron mesoscopic or macromolecular conducting ring is shown to support persistent currents due to Aharonov-Bohm flux, and the "spontaneous" persistent currents without the flux when structural transformation in the ring is blocked by strong coupling to the externally azimuthal-symmetric environment. In the free-standing macromolecular ring, symmetry breaking removes the azimuthal periodicity which however is further restored at the increasing field. Three-site ring with one or three electrons represent an interesting quantum system which can serve as a qubit (quantum bit of information) and a qugate (quantum logical gate). © 2005 by World Scientific Publishing Co. Pte. Ltd.EnglishMacromoleculesQuantum computersQuantum opticsAharonov-Bohm fluxConducting ringFixed numbersPersistent currentsQuantum systemStrong couplingStructural transformationSymmetry-breakingSuperconducting materialsBook Chapter10.1142/9789812701619_0006