Vacuum Particle Creation: Analogy with the Bloch Theory in Solid State Physics

A nonperturbative kinetic description of interband tunneling under the action of a strong electric field (dy-namical analogue of the Zener effect) is presented. The developed approach is based on the similarity to the Sauter-Schwinger effect and its dynamical analogue in QED. The kinetic equation for electron-hole quasipar-ticle excitations is derived on a dynamical basis in the framework of the oscillator representation. Numerical estimates are made for some simple cases of external fields. Detailed comparisons with the method based on the Bloch equations for electron-hole systems interacting with a time dependent electric field are performed. The proposed approach is an alternative to the Bloch theory and does not use the dipole approximation. This leads to predictions which differ from the ones based on the Bloch equations, in particular, concerning the frequency dependence of the absorption coefficient. c © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim