Antiresonance scattering at defect levels in the quantum conductance of a one-dimensional system

For the ballistic quantum transport, the conductance of each channel is quantized to a value of 2e²/h. In the presence of defects, electrons will be scattered such that the conductance will deviate from the values of the quantized conductance. We show that an antiresonance scattering can occur when an extra defect level is introduced into a conduction band. At the antiresonance scattering, exactly one quantum conductance of a one-dimensional wire disappears, in good agreement with ab initio calculations. The conductance takes a nonzero value when the Fermi energy is away from the antiresonance scattering.