Ballistic transport of electronic excitations and coherent light propagation in semiconductor quantum wells

Il Nuovo Cimento D - The transport of radiative and electronic excitations in coherently driven semiconductor quantum wells is analysed. On ultrashort time scales the spatial dynamics is determined...     

Microscopic theory of laser gain in semiconductor quantum wells

Received: 31 October 1997/Accepted: 31 October 1997     

Comparison of variational approaches for the exactly solvable 1/r-Hubbard chain

We study Hartree-Fock, Gutzwiller, Baeriswyl, and combined Gutzwiller-Baeriswyl wave functions for the exactly solvable one-dimensional 1/r-Hubbard model. We find that none of these variational wave functions is able to correctly reproduce the physics of the metal-to-insulator transition which occurs in the model for halffilled bands when the interaction strength equals the bandwidth. The many-particle problem to calculate the variational ground state energy for the Baeriswyl and combined Gutzwiller-Baeriswyl wave function is exactly solved for the 1/r-Hubbard model. The latter wave function becomes exact both for small and large interaction strength, but it incorrectly predicts the metal-to-insulator transition to happen at infinitely strong interactions. It is thus seen that neither Hartree-Fock nor an energetically excellent Jastrow-type wave function yield a reliable prediction on the zero temperature phase transition in the one-dimensional 1/r-Hubbard chain.     

To Martin C. Gutzwiller on His Seventy-Fifth Birthday

Editorial Introduction

To Martin C. Gutzwiller on His Seventy-Fifth Birthday