Tetsuro Sakuma

Computer-Simulated Scattering of Lattice Solitons from a Mass Interface in a One-Dimensional Nonlinear Lattice

The scattering of lattice solitons from a mass interface is numerically investigated. For this purpose, a rarefactive soliton solution for the generalized KdV equation is introduced in a one-dimensional nonlinear lattice as the incident soliton. The simulated results show that when the incident soliton propagates into an interface, it disintegrates into a reflected and a transmitted soliton. It is also found that the dependence of the reflected and transmitted soliton amplitudes on the mass ratio of the interface agrees quite well with that obtained from the boundary value problem of a simple linear wave equation. This is probably due to the weak nonlinearity of our lattice.

Computer-Simulated Scattering of Lattice Solitons from Impurity at Free Boundary

The scattering of solitons from a mass-impurity at a free boundary in a one-dimensional nonlinear lattice is investigated numerically. A rarefactive soliton solution for the generalized Korteweg-de Vries equation is introduced in this lattice as the incident soliton. The results show that the soliton interacts strongly with heavy impurity but very weakly with light one. These are discussed in terms of the spectral analysis of the incident soliton amplitude.

Damping of elastic surface waves by density fluctuation on solid surfaces

We investigate theroetically the damping rate of elastic surface waves due to density fluctuation on solid surfaces. A formula for the damping rate is presented using the Green’s function. The frequency and correlation length dependence of the rate is calculated. The results show a frequency and correlation length dependence quite different from that of the bulk phonon case.

Attenuation of elastic surface waves by anharmonic interactions at low temperatures

Based on the theory of surfons, we present a formalism to calculate the attenuation rate of elastic surface waves at low temperatures in the high‐frequency region. A general formula for the attenuation rate due to the cubic anharmonic terms in the elastic energy of an isotropic elastic continuum is given by means of a temperature‐dependent Greens function. In a frequency region between 20 and 40 GHz at T=1°K, our result shows quite different frequency and temperature dependence ω1+n T4−n (1.9 ≲ n ≲ 2.2) from that obtained in the low‐frequency region.

Damping of elastic surface waves by density fluctuation on solid surfaces. II. Depth effects of density fluctuation

We investigate theoretically the damping rate of elastic surface waves due to the density fluctuation on solid surfaces. In a previous work, we presented the formula for the damping rate due to density fluctuation localized on solid surfaces. We extend the previous work to allow the density fluctuation with finite depth from surface. The decay processes considered are from Rayleigh mode to Rayleigh mode and to total reflection mode. The finite depth effects of density fluctuation makes the damping rate quite different from that for the case of the density fluctuation localized on solid surfaces.

Thermal conductivity in two-dimensional monatomic non-linear lattices

The authors investigate the validity of Fouriers law in a two-dimensional monoatomic Toda lattice using the molecular dynamics method. The temperature profiles in the lattice exhibit an exponential behaviour with lattice position. The temperature dependence of thermal conductivity is necessarily derived from the spatial variation of the local temperature, and found to be inversely proportional to the local temperature. The validity of Fouriers law is confirmed by excluding the non-diffusive heat flow from the total heat currents.

Tunable single-photon source using Korteweg–de Vries solitons

We describe the quantum transport of electrons by solitary waves and use it as the basis for a scheme for generating a single photon with highly nonclassical nature. A concave soliton acting as an attractive potential can capture an electron in its only eigenstate and the captured electron can be transported by soliton propagation. A single photon is generated by a transition between eigenstates in the interacting soliton potential when a soliton with a captured electron interacts with an empty soliton with a lower eigenstate.

The attenuation of elastic waves by surface inhomogeneities: Rayleigh waves

We present a theoretical study of the attenuation of Rayleigh waves as a consequence of their interaction with surface inhomogeneities. The frequency and correlation‐length dependence of the attenuation rate is calculated explicitly based on a Gaussian‐distributed fluctuation for the mass density and for the Lame coefficients in terms of the Green’s function method. All the surface modes of elastic waves are considered in the attenuation processes.

Associated Production in Pion-Nucleon Collisions and Effects of Resonant States

Possibilities of explaining experimental features, angular distributions, polarization, and total cross sections in the reaction pi + p yields K0 + lambda at 910 Mev by considering N?* ( pi -N third resonance), Y* ( pi -A resonance), and K (Kresonance) are investigated. Calculations are presented in graphical and tabular forms. (L.N.N.)

The thermal conductivity in one-dimensional monatomic lattices with harmonic and quartic interatomic potentials

We analyse heat transport phenomena in a one-dimensional monatomic lattice with harmonic and quartic interatomic potentials by means of the molecular dynamics technique, paying special attention to non-diffusive heat flow and local temperature profiles in steady nonequilibrium states. The non-diffusive heat current is attributed to modified KDV solitons, which decay through collisions with phonons with short wavelengths. Hence, the non-diffusive heat flow does not propagate beyond a critical distance Icf. We confirm the anomalous diffusion of energy due to non-diffusive heat flow in steady non-equilibrium states for systems smaller than the critical length Icr. The non-diffusive heat current does not contribute to the total heat flow for lattices larger than the critical length Icr. The existence of Fouriers law is confirmed from first principles for the lattices. The temperature profiles become linear, and the resultant thermal conductivity is independent of the local temperatures of the lattice, in accordance with the temperatures profiles, so the local energy conservation law holds.