19,290 research outputs found
Wigner distribution function formalism for superconductors and collisionless dynamics of the superconducting order parameter
A technique to study collisionless dynamics of a homogeneous superconducting
system is developed, which is based on Riccati parametrization of Wigner
distribution function. The quantum evolution of the superconductiung order
parameter, initially deviated from the equilibrium value, is calculated using
this technique. The effect of a time-dependent BCS paring interaction on the
dynamics of the order parameter is also studied.Comment: 14 pages, 5 figure
Statistical properties of energy levels of chaotic systems: Wigner or non-Wigner
For systems whose classical dynamics is chaotic, it is generally believed
that the local statistical properties of the quantum energy levels are well
described by Random Matrix Theory. We present here two counterexamples - the
hydrogen atom in a magnetic field and the quartic oscillator - which display
nearest neighbor statistics strongly different from the usual Wigner
distribution. We interpret the results with a simple model using a set of
regular states coupled to a set of chaotic states modeled by a random matrix.Comment: 10 pages, Revtex 3.0 + 4 .ps figures tar-compressed using uufiles
package, use csh to unpack (on Unix machine), to be published in Phys. Rev.
Let
- …