Events at Physics |
Events During the Week of May 17th through May 24th, 2009
Monday, May 18th, 2009
- Plasma Theory Seminar
- Elgenmode Decomposition of Nonlinear Gyrokinetic Turbulence Simulations
- Time: 4:00 pm
- Place: 514 ERB
- Speaker: David Hatch, UW-Madison, Dept of Physics/Plasma
Tuesday, May 19th, 2009
- R. G. Herb Condensed Matter Seminar
- Electrical Control of a Hydrogenic Donor's Spin in Semiconductor Nanostructures
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Amrit De, University of Iowa
- Abstract: A quantum-information processing scheme based on electric-field dependent manipulation of spin-information for a shallow hydrogenic impurity is investigated. Calculations for electrical g tensor modulation for a single Silicon donor embedded in a GaAs-substrate is done by extending the effective mass treatment of shallow donors to the 8-band k.p model. The electric-field(E) quenches the donor electron's orbital angular momentum by altering quantum-confinement which modulates the g tensor. The calculated g-factors are highly nonlinear functions of the applied electric and magnetic fields and is unlike that seen in quantum dots. This is attributed to the weaker nature of the confinement potential for a shallow donor atom. The donor electron's spin-dynamics, for the spin-split-1S level, was calculated exactly by using time evolution operators. It is seen that as a consequence of the nonlinear nature of g(E), spin-flip transitions can be made resonantly at subharmonics of the Larmor frequency. Possibilities of using 2D and 1D quantum confinement to obtain more rapid Rabi oscillations is being investigated. I will also briefly discuss some of our work on nanowires, which includes g-factor calculations for nanowhisker-quantum-dots, comparison with experiment and related pseudopotential band structure calculations.
- Host: Robert Joynt
Wednesday, May 20th, 2009
- No events scheduled
Thursday, May 21st, 2009
- R. G. Herb Condensed Matter Seminar
- Rare-earth impurities in conventional and unconventional superconductors: Pr-based filled-skutterudite and UPd2Al3
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Ilya Eremin, TU Braunschweig and MPI Physics of Complex Systems, Dresden
- Abstract: It is well known that scattering by magnetic impurities suppresses conventional s-wave superconductivity by destroying Cooper pairs in a singlet state. This situation, however, can change in the case of paramagnetic non-Kramers rare-earth impurities. In particular, the inelastic charge scattering of conduction electrons from the aspherical part of the 4f charge distribution may yield an increase of Tc for superconductors containing an impurity with crystal-field-split energy levels We analyze this behavior in the Pr-based filled-skutterudite compounds and UPd2Al3 systems.
- Host: Andrey Chubukov
Friday, May 22nd, 2009
- No events scheduled