Qiang's Research Gallery 2 |
Quantized vortices in Bose-Einstein condensates and
Superfluidity (find more details from Qiang's publications)
It is said that at temperatures close to absolute zero,
something amazing happens: the state of superfluidity
starts to appear.
Superfluidity is a phase of matter characterised by the
complete absence of viscosity, that is, a "fluid"
can flow endlessly without friction (resistance).|
Examples of superfluidity can be found in superconductors, Helium, and more recently in BEC gas. Quantized vortices are the signature of superfluidity.
When a bucket of water is placed on a rotating turn-table, gradually the water starts to rotate uniformly with the glass. Yet, the rotation of superfluid is inhomogeneous: it circulates around quantized vortex lines where the vorticity concentrate, and there is little vorticity outside of the lines.
Models to study the quantized vortices in BEC are often taken to be the Gross-Pitaevskii equations, which we have extensively studied and simulated.
There is a story of quantized vortices beyond rotation, as told in our PRL paper.
|BEC in symmetric trap, no rotation|
||BEC in symmetric trap, under rotation|
|Symmetric trap, different rotation frequency|
|Symmetric and nonsymmetric trap|
|BEC passing through cylinder (laser, details in PRL)|
|Illustration of BEC from MIT group|
Phy Rev A, Dec 2001
analyzing vortex state in BEC, similar to the G-L framework
numerical computations of vortex solutions, 2d
Phy Rev Lett., 91 (2003), 090407
analyzing a recent MIT experiments with the laser probing of the BEC,
explains the onset of dissipation and its relation to vortex shedding
SIAM J. Sci. Comp., 25, pp. 1674-1697, 2004
SIAM J. Scientific Comp., 66, pp. 758-786, 2006
Contemp Math. 329, pp105-117, AMS, 2003.