A semiclassical theory of quantum noise in open chaotic systems

We consider the quantum evolution of classically chaotic systems in contact with surroundings. Based on $\hbar$-scaling of an equation for time evolution of the Wigner's quasi-probability distribution function in presence of dissipation and thermal diffusion we derive a semiclassical equation for quantum fluctuations. This identifies an early regime of evolution dominated by fluctuations in the curvature of the potential due to classical chaos and dissipation. A stochastic treatment of this classical fluctuations leads us to a Fokker-Planck equation which is reminiscent of Kramers' equation for thermally activated processes. This reveals an interplay of three aspects of evolution of quantum noise in weakly dissipative open systems; the reversible Liouville flow, the irreversible chaotic diffusion which is characteristic of the system itself, and irreversible dissipation induced by the external reservoir. It has been demonstrated that in the dissipation-free case a competition between Liouville flow in the contracting direction of phase space and chaotic diffusion sets a critical width in the Wigner function for quantum fluctuations. We also show how the initial quantum noise gets amplified by classical chaos and ultimately equilibrated under the influence of dissipation. We establish that there exists a critical limit to the expansion of phase space. The limit is determined by chaotic diffusion and dissipation. Making use of appropriate quantum-classical correspondence we verify the semiclassical analysis by the fully quantum simulation in a chaotic quartic oscillator.Comment: Plain Latex, 27 pages, 6 ps figure, To appear in Physica

Spacelab baseline ECS trace contaminant removal test program

An estimate of the Spacelab Baseline Environmental Control System's contaminated removal capability was required to allow determination of the need for a supplemental trace contaminant removal system. Results from a test program to determine this removal capability are presented

Explaining the Labor Force Participation of Women 20-24

Between about the mid 1960s and the late 1970s there was a remarkable rise in the labor force participation of women and then a leveling off that has persisted through the mid 1990s. This paper attempts to explain the labor force participation of women 20-24 over this period. A "relative income" variable is constructed based on Easterlin's (1980) relative income hypothesis, and this is found to be an important explanatory variable. Easterlin's "cohort wage" hypothesis is also used in the analysis. The basic equation estimated does very well in various tests that were performed on it, and it appears to explain well the rapid rise and then leveling off of the labor force participation of young women.