Exciton-Mott physics in a quasi-one-dimensional electron-hole system.

We investigate the correlation effect in the quasi-one-dimensional electron-hole (e-h) system under thermal equilibrium. A self-consistent screened T-matrix approximation developed here enables the description of an e-h pair under any ionization ratio, the portion of quasielectrons or quasiholes moving almost freely. Our phase diagram on the ionization ratio provides a unified description of exciton Mott physics from the low-density exciton gas towards the high-density electron-hole plasma, and predicts a first order transition at low temperature. The interband optical absorption-gain spectra are also evaluated, which succeeded in explaining semiquantitatively all aspects of the recent experimental observations in the strongly photoexcited quantum wires.