Calendar of Physics Talks Vienna
|Coherent optoelectronics with quantum dots|
|Speaker:||Artur Zrenner (Universität Paderborn und Center for Optoelectronics and Photonics Paderborn (CeOPP))|
|Abstract:||In optical experiments on single self-assembled InGaAs quantum dots the exciton ground state transition appears as a two-level system with a lifetime limited line width of a few µeV . For the case of pulsed laser fields and in the absence of decoherence, the ground state exciton represents a qubit. Excitations with ps laser pulses result in qubit rotations. Using state projection by tunnelling and photocurrent detection, the state readout can be performed in quantitative way [2, 3].
As a function of electric field induced detuning Ramsey fringes of a single exciton qubit can be observed and controlled for double pulse excitation [4, 5]. In such experiments it is possible to demonstrate voltage controlled qubit manipulations within a wide range of pulse delays.
Using fast electric signals, which are phase-locked to ps-laser pulses, the coherent control of an exciton qubit can be obtained by electric switching . Such voltage controlled qubit manipulations seem to be essential for new types of optoelectronic quantum gates and novel applications in the field of coherent optoelectronics.
 S. Stufler, P. Ester, A. Zrenner, and M. Bichler, Appl. Phys. Lett. 85, 4202 (2004).
 A. Zrenner, E. Beham, S. Stufler, F. Findeis, M. Bichler, and G.Abstreiter, Nature 418, 612 (2002).
 S. Stufler, P. Ester, A. Zrenner, and M. Bichler, Phys. Rev. B 72, 121301 (2005).
 S. Michaelis de Vasconcellos, S. Stufler, S.-A. Wegner, P. Ester, A. Zrenner, and M. Bichler, Phys. Rev. B 74, 081304(R) (2006).
 S. Stufler, P. Ester, A. Zrenner, and M. Bichler, Phys. Rev. Lett. 96, 037402 (2006).
 S. Michaelis de Vasconcellos, S. Gordon, M. Bichler, T. Meier and A. Zrenner, Nature Photonics 4, 548 (2010).
|Date:|| Mon, 04.10.2010|
|Duration:|| 60 min|
|Location:||TU Wien / Institute of Photonics, Seminarraum 387 Gusshausstraße 27 – 29, Neues EI, Stiege II, Erdgeschoß, 1040 Wien|
|Contact:||Prof. Karl Unterrainer / Thomas Moldaschl|
|Instabilities in the Quark-Gluon Plasma |
|Speaker:||Maximilian Attems (TU Wien)|
|Abstract:||The quark-gluon plasma (QGP) is a phase at extremely high temperatures formed by deconfined quarks and gluons as predicted by quantum chromodynamics (QCD). Non-Abelian plasma instabilities play a crucial role in the nonequilibrium dynamics of a weakly coupled QGP. The evolution of Chromo-Weibel instabilties can be carried out thanks to real-time lattice simulations. The developed hard-expanding-loop (HEL) formalism allows the (numerical) calculation of the time evolution of gluonic mean fields in full 3 dimensional Bjorken expansion. |
|Date:|| Tue, 05.10.2010|
|Duration:|| 60 min|
|Location:||Uni Wien (Boltzmanngasse 5, 5th floor, Schrödinger HS / large seminar room)|