Chain of Superconducting Loops as a Possible Quantum Register

The idea of the quantum computation is based on paradoxical principles of quantum physics, superposition and entanglement of quantum states. This idea looks well-founded on the microscopic level in spite of the absence of an universally recognized interpretation of these paradoxical principles since they were corroborated over and over again by reliable experiments on the microscopic level. But the technology can not be able in the near future to work on the microscopic level. Therefore macroscopic quantum phenomenon - superconductivity is very attractive for the realization of the idea of quantum computer. It is shown in the present paper that a chain of superconducting loops can be only possible quantum register. The proposals by some authors to provide the EPR correlation with help of a classical interaction witness the misunderstanding of the entanglement essence. The problem of the possibility of superposition of macroscopically distinct states is considered.Comment: 10 pages, 0 figure. Presented at International Symposium "Quantum Informatics 2004" Moscow, October 5-8, 200

Interpretación del contenido del principio de “estado social” en la legislación y los cargos de la Corte Suprema de Canadá

This paper is devoted to the analysis of the constitutional principle of “state sociality” in Canada, taking into account the implemented model of a social state. The method and features of securing the guarantees of the sociality of a state in the constitutional legislation of Canada are shown. Based on the analysis of the legislation, the authors made conclusions about the specifics of the sociality of the state in Canada. Analyzing the reflection of the “state sociality” principle in the judicial practice of the Supreme Court of Canada, the authors summarized its influence on the problems of a welfare state.Este artículo está dedicado al análisis del principio constitucional de la “sociedad estatal” en Canadá, teniendo en cuenta el modelo implementado de un estado social. Se muestran el método y las características de asegurar las garantías de la sociedad de un estado en la legislación constitucional de Canadá. Basado en el análisis de la legislación, los autores sacaron conclusiones sobre los detalles de la sociedad del estado en Canadá. Analizando el reflejo del principio de “sociedad estatal” en la práctica judicial de la Corte Suprema de Canadá, los autores resumieron su influencia en los problemas de un estado de bienestar

RKKY interaction in Layered Superconductors with Anisotropic Pairing

The RKKY interaction between rare-earth (RE) ions in high-$T_c$ superconductors is considered at $T\ll T_c$. It is shown that this interaction consists of two terms: conventional oscillating one and the positive term, which is proportional to the gap function and decreases in the $2D$ case inversely proportional to the distance. In the antiferromagnetic state of the RE subsystem this positive interaction gives rise for frustrations which diminishes the Neel temperature. In the case of strongly anisotropic gap function this frustration produces two different values of the effective nearest neighbor exchange coupling between RE ions along the $a$ and $b$. This anisotropy has been established experimentally in Ref.\cite{6,7,8}.Comment: 10 pages, REVTEX, no figure

Optical Phonon Lineshapes and Transport in Metallic Carbon Nanotubes under High Bias Voltage

We calculate the current-voltage characteristic of metallic nanotubes at high bias voltage showing that a bottleneck exists for short nanotubes in contrast to large ones. We attribute this to a redistribution of lower-lying acoustic phonons caused by phonon-phonon scattering with hot optical phonons. The current-voltage characteristic and the electron and phonon distribution functions are derived analytically, and serve to obtain in a self-contained way the frequency shift and line broadening of the zone center optical phonons due to the electron-phonon coupling at high bias. We obtain a positive frequency shift from the zero bias shift and no broadening of the optical phonon mode at very high voltages, in agreement with recent experiments.Comment: 16 pages, 8 figures, minor changes, pusblished in PR