Low-temperature thermionic emitter Final report, 9 Feb. 1969 - 9 Apr. 1970

Fabrication processes for integrated vacuum circuits and life tests of dual triodes for low temperature thermionic emitter

Theory of light-induced current in molecular-tunneling junctions excited with intense shaped pulses

A theory for light-induced current by strong optical pulses in molecular-tunneling junctions is described. We consider a molecular bridge represented by its highest occupied and lowest unoccupied levels, HOMO and LUMO, respectively. We take into account two types of couplings between the molecule and the metal leads: electron transfer that gives rise to net current in the biased junction and energy transfer between the molecule and electron-hole excitations in the leads. Using a Markovian approximation, we derive a closed system of equations for the expectation values of the relevant variables: populations and molecular polarization that are binary, and exciton populations that are tetradic in the annihilation and creation operators for electrons in the molecular states. We have proposed an optical control method using chirped pulses for enhancing charge transfer in unbiased junctions where the bridging molecule is characterized by a strong charge-transfer transition. An approximate analytical solution of the resulting dynamical equation is supported by a full numerical solution. When energy transfer between the molecule and electron-hole excitations in the leads is absent, the optical control problem for inducing charge transfer with linearly chirped pulse can be reduced to the Landau-Zener transition to a decaying level. When chirp is fast with respect to the rate of the electron transfer, the Landau theory is recovered. The proposed control mechanism is potentially useful for developing novel opto-electronic single-electron devices with optical gating based on molecular nanojunctions.Comment: 14 pages, 7 figures; submitted to PR

MTRAC - A computer program for analysis of circuits including magnetic cores. Volume 2 - Input data and program listing

Input data cards program listing for MTRA

A spin-boson thermal rectifier

Rectification of heat transfer in nanodevices can be realized by combining the system inherent anharmonicity with structural asymmetry. we analyze this phenomenon within the simplest anharmonic system -a spin-boson nanojunction model. We consider two variants of the model that yield, for the first time, analytical solutions: a linear separable model in which the heat reservoirs contribute additively, and a non-separable model suitable for a stronger system-bath interaction. Both models show asymmetric (rectifying) heat conduction when the couplings to the heat reservoirs are different.Comment: 5 pages, 3 figures, RevTeX

Flux switching in multipath cores

Flux switching in multipath ferrimagnetic core materials - computational analyses for unloaded core, loaded core, core-diode-transistor binary counter, and loaded three-leg cor

The projection of a nonlocal mechanical system onto the irreversible generalized Langevin equation, II: Numerical simulations

The irreversible generalized Langevin equation (iGLE) contains a nonstationary friction kernel that in certain limits reduces to the GLE with space-dependent friction. For more general forms of the friction kernel, the iGLE was previously shown to be the projection of a mechanical system with a time-dependent Hamiltonian. [R. Hernandez, J. Chem. Phys. 110, 7701 (1999)] In the present work, the corresponding open Hamiltonian system is further explored. Numerical simulations of this mechanical system illustrate that the time dependence of the observed total energy and the correlations of the solvent force are in precise agreement with the projected iGLE.Comment: 8 pages, 9 figures, submitted to J. Chem. Phy

MTRAC - A computer program for analysis of circuits including magnetic cores. Volume 1 - Computation, program, and application Final report

Method of computation, organization, and applications of Modified transient analysis by compute

Exact analytical evaluation of time dependent transmission coefficient from the method of reactive flux for an inverted parabolic barrier

In this paper we derive a general expression for the transmission coefficient using the method of reactive flux for a particle coupled to a harmonic bath surmounting a one dimensional inverted parabolic barrier. Unlike Kohen and Tannor [J. Chem. Phys. 103, 6013 (1995)] we use a normal mode analysis where the unstable and the other modes have a complete physical meaning. Importantly our approach results a very general expression for the time dependent transmission coefficient not restricted to overdamped limit. Once the spectral density for the problem is know one can use our formula to evaluate the time dependent transmission coefficient. We have done the calculations with time dependent friction used by Xie [Phys. Rev. Lett 93, 180603 (2004)] and also the one used by Kohen and Tannor [J. Chem. Phys. 103, 6013 (1995)]. Like the formula of Kohen and Tannor our formula also reproduces the results of transition state theory as well as the Kramers theory in the limits t->0 and t->infinity respectively

Flux switching in magnetic circuits

Flux switching in magnetic circuit