Ülo Parts, defendant

Dissertation on Wednesday 15.3.95 at 12:00

in Helsinki University of Technology, Auditorium F1


Measurements of the Structure and Nucleation of Vorticity in the 3He Superfluids


The Thesis treats the creation, structure and dynamics of topological objects in rotating superfluid 3He. These objects appear when a system cools down and undergoes a phase transition to a state of reduced symmetry. When a liquid solidifies the symmetry is not continuous any more but limited by the crystal structure. In a crystalline material planar grainboundaries, linear dislocations and point defects are topological defects. In a superfluid the defects are formed in a continuous order parameter field generated by the medium.

The thesis describes research using NMR on two different superfluids formed by the isotope 3He. When a superfluid in a cylindrical vessel is rotated, quantized vortices are formed. For the first time a single vortex and its quantization has been observed. Two new vortex structures have been found which increases the total number of vortex types to 8.

3He provides a unique physical system where in the laboratory one can investigate topological objects formed in a continuous coherent vector field. The results can be viewed in the light of quantum field theories of particle physics and cosmology.


Professor George Pickett from Lancaster University, School of Physics & Chemistry .

Peter Berglund <peter@neuro.hut.fi>