Magnetic Field Effect on an Electron Tunneling out of a Confining Plane

The influence of a magnetic field on the tunneling of an electron out of a confining plane is studied by a path integral method. We map this 3-d problem on to a 1-d one, and find that the tunneling is strongly affected by the field. Without a perpendicular field the tunneling at zero temperature can be completely suppressed by a large parallel field, but in the small parallel field and low temperature limit the tunneling rate is finite. An explicit formula is obtained in this case. A quantitative explanation without fitting parameter to a recent experiment is provided.Comment: latex, 11 page

Dynamical Correlation Theory for an Escape Process

A dynamical theory which incorporates the electron-electron correlations and the effects of external magnetic fields for an electron escaping from a helium surface is presented. The degrees of freedom in the calculation of the escape rate is reduced from $3N$ to 3 as compared with other approach. Explicit expressions for the escape rate in various situations are obtained. In particular, in the weak parallel magnetic field limit the tunneling rate has an exponential dependence quadratic with magnetic field strength and an unusual exponential increase linear with temperature.Comment: 12pages latex, University of Washington, Seattl

Nonequilibrium Steady State Driven by a Nonlinear Drift Force

We investigate the properties of the nonequilibrium steady state for the stochastic system driven by a nonlinear drift force and influenced by noises which are not identically and independently distributed. The nonequilibrium steady state (NESS) current results from a residual part of the drift force which is not cancelled by the diffusive action of noises. From our previous study for the linear drift force the NESS current was found to circulate on the equiprobability surface with the maximum at a stable fixed point of the drift force. For the nonlinear drift force, we use the perturbation theory with respect to the cubic and quartic coefficients of the drift force. We find an interesting potential landscape picture where the probability maximum shifts from the fixed point of the drift force and, furthermore, the NESS current has a nontrivial circulation which flows off the equiprobability surface and has various centers not located at the probability maximum. The theoretical result is well confirmed by the computer simulation.Comment: 10 pages, 4 figure

Nonlinear Schr\"odinger Equation for Superconductors

Using the Hartree-Fock-Bogoliubov factorization of the density matrix and the Born-Oppenheimer approximation we show that the motion of the condensate satisfies a nonlinear Schr\"odinger equation in the zero temperature limit. The Galilean invariance of the equation is explicitly manifested. {}From this equation some general properties of a superconductor, such as Josephson effects, the Magnus force, and the Bogoliubov-Anderson mode can be obtained readily.Comment: Latex, 12 page