Kondenserede fasers fysik (væskeform og faststoffysik)

The characteristics of electrical contacts have long attracted the attention of researchers since these contacts are used in every electrical and electronic device. Earlier studies generally considered electrical contacts of large dimensions, having regions of current concentration with diameters substantially larger than the characteristic dimensions of the material: the interatomic distance, the mean free path for electrons, the coherence length in the superconducting state, etc. [110]. The development of microelectronics presented to scientists and engineers the task of studying the characteristics of electrical contacts with ultra-small dimensions. Characteristics of point contacts such as mechanical stability under continuous current loads, the magnitudes of electrical fluctuations, inherent sensitivity in radio devices and nonlinear characteristics in connection with electromagnetic radiation can not be understood and altered in the required way without knowledge of the physical processes occurring in contacts. Until recently it was thought that the electrical conductivity of contacts with direct conductance (without tunneling or semiconducting barriers) obeyed Ohm's law. Nonlinearities of the current-voltage characteristics were explained by joule heating of the metal in the region of the contact. However, studies of the current-voltage characteristics of metallic point contacts at low (liquid helium) temperatures [142] showed that heating effects were negligible in many cases and the nonlinear characteristics under these conditions were observed to take the form of the energy dependent probability of inelastic electron scattering, induced by various mechanisms.

Based on the interactive program Interquanta, Quantum Mechanics on the Macintosh, uses extensive 3-D graphics to guide the student through computer experiments in the quantum mechanics of free particle motion, bound states and scattering, tunneling, two-particle interactions, and more. It also includes a section on special functions of mathematical physics. With more than 200 problems, the text and programs provide students with practical experiences in using such hard-to-visualize concepts as complex amplitudes, eigenvalues, and scattering cross sections. The diskette included with the book provides two versions of the programs, one for use in computers with a mathematical coprocessor, the other optimized for machines without a coprocessor. For this new edition the software has been updated and extended.