Observation of sharp collective excitations of the one-dimensional electron gas in cleaved-edge-overgrown semiconductor quantum wires

Coulomb interactions in a dilute one-dimensional (1D) electron system in high quality cleaved-edge overgrown GaAs quantum wires are probed by optics experiments. Intra-subband collective excitation modes are observed in resonant inelastic light-scattering spectra. A sharp intra-subband excitation occurs close to the single particle transition energy. It is narrower and weaker than the plasmon band, and its width is consistent with electron mean free paths in the micrometer range. Scattering intensities display large enhancements only for scattered photon energies in resonance with the optical gap of the wires. Preliminary analysis reveals impact of interactions in the 1D system. Possible interpretation in terms of Luttinger-liquid bosons is discussed.