FWI Institutskolloquium: "Ultrafast quantum optics, plasmonics, and spintronics with solid-state nanosystems"

Date

Mar 24, 2011

Time

10:30 AM - 12:00 PM

Speaker

Prof. Dr. Rudolf Bratschitsch (Institut für Physik, TU Chemnitz)

Language

de

Main Topic

Physik

Other Topics

Physik

Host

Susann Gebel (2345)

Description

Semiconductor quantum dots are promising solid-state systems for fundamental quantum optical experiments and robust quantum information processing. In quantum dots, ultrafast sequences of coherent quantum operations may be envisioned with femtosecond light pulses. We present the first femtosecond pump-probe experiment on a single CdSe nanocrystal. In this few-fermion system, Coulomb renormalization and single-photon gain are observed on an ultrafast timescale [1]. To increase the coupling of light to the nanoscopic light emitter, we fabricate optical nanoantennas and investigate their linear [2] and nonlinear [3] optical properties.
The second part of my talk deals with the ultrafast spin dynamics in wide-gap magnetic semiconductors based on GaN or ZnO, which are interesting for room-temperature applications. We perform time-resolved Faraday rotation measurements in the ultraviolet on colloidal ZnO quantum dots [4] and on magnetically doped bulk ZnO to reveal the ultrafast spin dynamics. We discuss the relevant spin dephasing mechanisms governed by charge-separated states and electron-magnetic ion coupling.
References
[1] F. Sotier et al., Nature Physics 5, 352 (2009).
[2] J. Merlein et al., Nature Photonics 2, 230 (2008).
[3] T. Hanke et al., Phys. Rev. Lett. 103, 257404 (2009).
[4] N. Janssen et al., Nano Lett. 8, 1991 (2008)

Last modified: May 27, 2011, 4:37:42 PM