Berlin 2008 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 15: Superconductivity: Poster Session

TT 15.25: Poster

Dienstag, 26. Februar 2008, 14:00–18:00, Poster B

The nonadiabatic regime in optically excited BCS superconductors — •Thomas Papenkort¹, Vollrath Martin Axt², and Tilmann Kuhn¹ — ¹Institut für Festkörpertheorie, Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster — ²Institut für Theoretische Physik III, Universität Bayreuth, 95440 Bayreuth

We have calculated the coherent dynamics of a BCS superconductor excited by short laser pulses using the density matrix formalism in mean field approximation. For very short pulses a nonadiabatic regime emerges in which the superconductor is put into a state with nonvanishing quasiparticle coherences. For such states the modulus of the BCS order parameter performs a damped oscillation in time. It turns out that this oscillation cannot be measured by means of pump-probe spectroscopy as only its temporal mean is reflected in the spectra. However we will show that this drawback can be overcome by using two coherent pump pulses.