Self-consistent quantum-kinetic theory for interplay between pulsed-laser excitation and nonlinear carrier transport in a quantum-wire array

Self-consistent quantum-kinetic theory for interacting drifting electrons and force-driven phonons in a 1D system

A self-consistent quantum-kinetic model is developed for studying strong-field nonlinear electron transport interacting with force-driven phonons within a nanowire system. For this model, phonons can be dragged into motion through strong electron-phonon scattering by fast-moving electrons along the opposite direction of the DC electric field. Meanwhile, the DC-field induced charge current of electrons can be either enhanced or reduced by the same electron-phonon scattering, depending on the relative direction of a DC field with respect to that of an applied temperature gradient for driving phonons. By making use of this quantum-kinetic model beyond the relaxation-time approximation, neither electron nor phonon temperature is required for describing ultrafast electron-phonon scattering and their correlated transports in this 1D electronic-lattice system.

Ultrafast transverse and longitudinal response of laser-excited quantum wires

We couple 1D pulse propagation simulations with laser-solid dynamics in a GaAs quantum wire, solving for the electron and hole populations and the interband and intraband coherences between states. We thus model not only the dynamical dipole contributions to the optical polarization (interband bound-charge response) but also the photo-generation and back-action effects of the net free-charge density (intraband free-charge response). These results show that solving for the dynamic electron and hole intraband coherences leads to plasma oscillations at THz frequencies, even in a 1D solid where plasma screening is small. We then calculate the transverse and longitudinal response of the quantum wire and characterize the dispersion relation for the e-h plasma. This approach allows one to predict the optoelectronic response of 1D semiconductor devices during and after exposure to resonant ultrashort pulses.

Atomistic Band-Structure Computation for Investigating Coulomb Dephasing and Impurity Scattering Rates of Electrons in Graphene

In this paper, by introducing a generalized quantum-kinetic model which is coupled self-consistently with Maxwell and Boltzmann transport equations, we elucidate the significance of using input from first-principles band-structure computations for an accurate description of ultra-fast dephasing and scattering dynamics of electrons in graphene. In particular, we start with the tight-binding model (TBM) for calculating band structures of solid covalent crystals based on localized Wannier orbital functions, where the employed hopping integrals in TBM have been parameterized for various covalent bonds. After that, the general TBM formalism has been applied to graphene to obtain both band structures and wave functions of electrons beyond the regime of effective low-energy theory. As a specific example, these calculated eigenvalues and eigen vectors have been further utilized to compute the Bloch-function form factors and intrinsic Coulomb diagonal-dephasing rates for induced optical coherence of electron-hole pairs in spectral and polarization functions, as well as the energy-relaxation time from extrinsic impurity scattering of electrons for non-equilibrium occupation in band transport.