NONLINEAR DYNAMICS OF TWO-COMPONENT BOSE-EINSTEIN CONDENSATES
TITLE:
NONLINEAR DYNAMICS OF TWO-COMPONENT BOSE-EINSTEIN CONDENSATES
DATE:
Friday, October 15th, 2010
TIME:
3:30 PM
LOCATION:
GMCS 214
SPEAKER:
Ricardo Carretero, Nonlinear Dynamical Systems (NLDS) Group, Department of Mathematics and Statistics
and Computational Science Research Center, San Diego State University
ABSTRACT:
In the 1920’s Bose and Einstein predicted that, for sufficiently cold temperatures, a collection of atoms should coalesce into the same quantum state forming a condensed lump of coherent matter. The experimental verification of Bose-Einstein condensates (BECs) remained elusive until 1995 when that year’s Nobel prize winners managed to achieve cold enough temperatures to observe condensation in a cloud of trapped ultra-cold Rubidium atoms (rightly dubbed as the “coldest place in the Universe”). Nowadays, there exists about 50 groups worldwide capable of producing BECs on demand and there is an enormous trend in the literature to understand the properties of these macroscopic lumps of quantum matter.
The macroscopic (mean-field) description of BECs, accounted for by a nonlinear Schroedinger equation subject to an external confining potential, allows for a diverse plethora of nonlinear waves and coherent structures (dark and bright solitons, vortices, vortex rings, vortex lattices, etc.) and their interactions. In this talk we describe the interaction dynamics between two repulsive atomic species in a harmonically confined two-component (i.e., two different atom clouds) BEC allowing us to obtain conditions for the miscibility between components. The method relies on employing a variational approach to obtain reduced equations of motion for the main parameters of each species. This corresponds to a simple classical Newtonian equation of motion where the components oscillate in an effective two-well potential accurately capturing the statics and dynamics of both species. Miscibility conditions for the inter-species coupling are then obtained as a function of the harmonic trap strength. We also study the full bifurcation scenario of phase separated states of increasing complexity that contain several interwoven domain walls as well as asymmetric states.
We will also briefly discuss a couple of current interesting directions including the inter-penetrating dynamics of two-components BECs (in association with an actual physical experiments) and the interaction of vortices across components.
HOST:
Jose Castillo
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