Events - Daily
March 14, 2013 >>
|Thursday, March 14|
PCTS/Condensed Matter Seminar - Salvatore R. Manmana, Goettingen University - Far-from-Equilibrium Quantum Magnetism with Ultracold Polar Molecules
Recent theory has indicated how to emulate tunable models of quantum magnetism with ultracold polar molecules.
Here we show that present molecule optical lattice experiments can accomplish three crucial goals for quantum emulation, despite currently being well below unit filling and not quantum degenerate. The first is to verify and benchmark the models proposed to describe these systems. The second is to prepare correlated and possibly useful states in well-understood regimes.
The third is to explore many-body physics inaccessible to existing theoretical techniques. Our proposal relies on a nonequilibrium protocol that can be viewed either as Ramsey spectroscopy or an interaction quench. The proposal uses only routine experimental tools available in any ultracold molecule experiment. To obtain a global understanding of the behavior, we treat short times pertubatively, develop analytic techniques to treat the Ising interaction limit, and apply a time-dependent density matrix renormalization group to disordered systems with long range interactions.
[PRL 110, 075301 (2013)]
Jadwin A09 · 1:15 p.m.– 2:30 p.m.
Hamilton Colloquium Series - William Young, Scripps Institution of Oceanography, UC, San Diego - "Two Dimensional Turbulence"
In the first part of this talk I will review basic results about two-dimensional turbulence emphasizing the absence of a dissipative anomaly in D=2, and the energy-conserving long-time behavior of solutions of the inviscid equations of motion. Arguments dating back to Onsager predict the formation of an en-semble of vortices separated by potential flow. Close encounters between like-signed vortices lead to irreversible merger into larger vortices. A simple scal-ing argument predicts relations between different quantities, such as the de-cay of the vortex density and the expansion in radius of a typical vortex. In the second part of the talk I will turn to forced two-dimensional turbulence and the problem of vortex condensation into the gravest mode of a finite box. I will show that for most forcing functions the amplitude of the condensate in the inviscid limit is independent of viscosity. This non-singular inviscid limit is compatible with the energy power integral because the flow adjusts so that the work done on the two-dimensional fluid by a prescribed force is linearly proportional to viscosity in the inviscid limit.
Jadwin A10 · 4:30 p.m.– 5:30 p.m.