Electronic transport in quantum waveguide systems with attached stubs

Single-mode quantum transmission properties of a quantum waveguide system with attached stubs are studied in the ballistic regime. The formation of energy bands is achieved in the case of periodic structure mainly around the energies where a single stub possesses antiresonances. A single defect in the otherwise periodic structure introduces a resonant (or an antiresonant) state. We find that this state is not an exponentially localized state, and is not a Fano-type resonance (although it originates from it), but more a well-known Lorentzian-shaped Breit-Wigner transmission resonance. When this state falls in the energy band, then it forms an antiresonance. A strong magnetic field creates additional quasibound states.