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https://hdl.handle.net/2142/35202
Description
Title
Little Big Bangs in Helium-Three
Author(s)
Warner, Geoffrey Lee
Issue Date
2004
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Helium-three
fermi
thermodynamics
semiclassical
formalism
anomalous
zurek
psuedospin
superfluidity
nucleation
Language
en
Abstract
With an eye toward the interpretation of so-called ‘cosmological’ experiments performed on the low temperature phases of 3He, in which regions of the superfluid are destroyed by local heating with neutron radiation, we have studied the properties of degenerate Fermi systems under certain extreme non-equilibrium conditions. First, we consider the dynamical evolution of localized hot spots in ultralow temperature Fermi
liquids. Within a model calculation, it is found that such perturbations do not relax into a hydrodynamic profile at long times, as might be expected of thermal hot spots under less exotic conditions. Instead, the hot spot expands outward into a shell moving away from its center at a velocity comparable to the Fermi velocity vF , which is consistent with the ‘baked Alaska’ hypothesis proposed earlier by Leggett as a possible solution to the riddle of B-phase nucleation in 3He. Second, we examine the behavior of a Fermi gas subjected to uniform variations of an attractive BCS interaction parameter . In 3He the quenches induced by the rapid cooling of the hot spots back through the transition may lead to the formation of vortex loops via the Kibble-Zurek mechanism. A consideration of the free energy available in the quenched region for the production of such vortices reveals that the Kibble-Zurek scaling law gives at best a lower bound on the defect spacing. Further, for quenches that fall far outside the Ginzburg-Landau regime, the dynamics of the pair subspace, as initiated by quantum fluctuations, tends irreversibly to a self-driven steady state with a gap 1 = C(e2/N(0) − 1)−1/2. In weak coupling this is half the equilibrium
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