Regensburg 1998 – scientific programme

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HL: Halbleiterphysik

HL 13: Ultrakurzzeitdynamik I

HL 13.8: Talk

Tuesday, March 24, 1998, 12:15–12:30, H16

Effective multi-band-picture for complex many-body phenomena: bound states, plasma oscillations etc. — •Nai Hang Kwong, Michael Bonitz, and Dietrich Kremp — FB Physik, Universit"at Rostock, Universit"atsplatz 3, 18051 Rostock

Inspired by the familiar Bloch equations, we present and extension of the underlying concept to more complicated systems. The Bloch equations allow for a treatment of two-particle bound states (excitons etc.) in terms of one-particle quantities (Wigner distribution, interband polarization). This picture is much simpler than the conventional two-particle description based on the Bethe-Salpether equation. We give a detailed comparison of the two approaches, discussing the potential and limitations of this analogy. In particular, the one-particle approach requires the application of an external field in contrast to the two-particle description. It is shown that the same idea may be extended to far more complex systems, including other types of bound states. Furthermore, it is demonstrated how one can use the “multi-band” picture to very efficiently describe plasma oscillations in generalized kinetic equations.