Coupled Semiconductor Bloch Equations for Studying Quantum Plasmas and Optical Responses of Photo-Generated Carriers in a Quantum Wire*

By employing semiconductor Bloch equations and solving for electron (e) and hole (h) occupation functions, as well as for inter-band/intra-band quantum coherences between/within e and h minibands, it enables us to couple one-dimensional (1D) pulse-propagation simulations with quantum kinetics for e and h in a quantum wire. As a result, dynamical dipole contributions, both from optical polarization (i.e. inter-band bound-charge response) and from photo-generation and back-action effects due to net free-charge density (i.e. intra-band free-charge response), can be incorporated in our first-principles physics model. In particular, our numerical results on dynamic e and h intra-band coherences display standing-wave-like longitudinal oscillations with time at THz frequencies, which are further accompanied by coulomb-renormalization of dispersion relations (i.e. dependence on either carrier or laser wave vector) with respect to both plasmon modes and phase velocity in laser-pulse propagation. Such a theoretical approach facilitates to predict accurately the full transient optoelectronic response of 1D semiconductor devices during and after exposure to a resonant ultrashort laser pulse.