COSMIC STRINGS IN LABORATORY SUPERFLUIDS AND THE TOPOLOGICAL REMNANTS OF OTHER PHASE-TRANSITIONS

Superfluid phase transition in He-4 can be accomplished through pressure quench on a short (dynamical) timescale. ''Vacuum condensate'' of the new, broken symmetry phase is the wavefunction of the superfluid Bose condensate with a certain ''trapped'' distribution of vortex lines. Analogous phase transitions from the false to the true vacuum are expected to occur in the early universe. There they are thought to leave behind topological defects such as strings. I calculate the density of strings (i.e., vortex lines) predicted by the application of the cosmological scenario to He-4. The proposed experiment tests key elements of the standard cosmological scenario for creation of topological defects - known as the Kibble mechanism - in a cryogenic setting. Analogous experiments can be performed in superconductors as well as in either phase of He-3, and have been already carried out by Yurke and his co-workers in liquid crystals.