Large optical singularities of the one-dimensional electron gas in semiconductor quantum wires

Modulation-doped quantum wire structures have been fabricated in the extreme quantum limit in which only the lowest one-dimensional (1D) subband is occupied by electrons. A pronounced Fermi edge singularity is observed for the first time in the absorption and emission spectra of the 1D electron gas. It has a strong temperature dependence determined by the Fermi energy and is much sharper than in two dimensions. The experimental results agree qualitatively with exact diagonalization studies of finite Hubbard chains.