Quantum-optical spectroscopy of semiconductors

The microscopic foundation of quantum-optical spectroscopy is presented. It is proposed to use this technique to generate and detect quasiparticle states in semiconductors whose quantum-statistical properties are governed by that of the exciting light. While resonant classical excitation induces an optical interband polarization, low-intensity quantum excitation directly seeds a quantum-degenerate exciton state which is characterized by long-range order, anomalous reduction of Coulomb and phonon scattering, as well as strongly enhanced and directional quantum emission.