Magnetoabsorption of far-infrared light in quantum wires: Jumps of the resonance frequency

We show that, in quantum wires with a parabolic confinement, smooth spatial fluctuations of the confinement potential along the wire lead to broadening of the far-infrared absorption spectrum and to a shift of the absorption maximum with respect to ideal quantum wires. The shift is determined by the screened fluctuations of the confining potential. The screening is due to the electron states at the Fermi surface, and, therefore, it changes drastically at certain values of the magnetic field when one of the hybrid electric-magnetic subbands becomes depopulated and the corresponding electron states at the Fermi surface vanish. This results in abrupt jumps of the position of the absorption maximum at these values of the magnetic field, explaining recent experimental data.