Low temperature decoherence and relaxation in charge Josephson-junction qubits

In this lectures, we have described some essential features of loss of coherence by a qubit coupled to the environment. We have first presented well known semiclassical arguments that relate both decoherence and relaxation to the environmental noise. Then we have shown that models with pure decoherence (but no relaxation in qubit states) can be exactly solvable. As an example, we have treated in detail the model of fluctuating background charges which is believed to describe one of the most important channels for decoherence for the charge Josephson junction qubit. We have shown that the decoherence rate saturates at `high' temperatures while becoming linear in T at low temperatures and showing in all regimes a non-monotonic behaviour as a function of the coupling of the qubit to the fluctuating background charges. We have also considered, albeit only perturbatively, the qubit relaxation by the background charges and demonstrated that a quasi-linear behaviour of the spectral density of noise deduced from the measurements of the relaxation rate can be qualitatively explained.Comment: Lecture notes for International workshop on mesoscopic and nanoscopic systems, Kolkata, India, February 2006, to be published by Springe

Future space transport

Prospects for the mastery of space and the basic problems which must be solved in developing systems for both manned and cargo spacecraft are examined. The achievements and flaws of rocket boosters are discussed as well as the use of reusable spacecraft. The need for orbiting satellite solar power plants and related astrionics for active control of large space structures for space stations and colonies in an age of space industrialization is demonstrated. Various forms of spacecraft propulsion are described including liquid propellant rocket engines, nuclear reactors, thermonuclear rocket engines, electrorocket engines, electromagnetic engines, magnetic gas dynamic generators, electromagnetic mass accelerators (rail guns), laser rocket engines, pulse nuclear rocket engines, ramjet thermonuclear rocket engines, and photon rockets. The possibilities of interstellar flight are assessed

Low-Temperature Decoherence of Qubit Coupled to Background Charges

We have found an exact expression for the decoherence rate of a Josephson charge qubit coupled to fluctuating background charges. At low temperatures $T$ the decoherence rate ${\Gamma}$ is linear in $T$ while at high temperatures it saturates in agreement with a known classical solution which, however, reached at surprisingly high $T$. In contrast to the classical picture, impurity states spread in a wide interval of energies ($\gg T$) may essentially contribute to ${\Gamma}$.Comment: Both figures are changed to illustrate a more generic case of impurity states spread in wide interval of energies. Some changes have been made to the abstract and the introductio

Ion cumulation by conical cathode electrolysis.

Results of solid-state sodium stearate electrolysis with conical and cylindrical cathodes is presented here. Both electric measurement and conical samples destruction can be explained if a stress developing inside the conical sample is much bigger than in the cylindrical case and there is its unlimited amplification along cone slopes. OTHER KEYWORDS: ion, current, solid, symmetry, cumulation, polarization, depolarization, ionic conductor,superionic conductor, ice, crystal, strain, V-center, V-centre, doped crystal, interstitial impurity, intrinsic color center, high pressure technology, Bridgman, anvil, experiment, crowdion, dielectric, proton, layer, defect, lattice, dynamics, electromigration, mobility, muon catalysis, concentration, doping, dopant, conductivity, pycnonuclear reaction, permittivity, dielectric constant, point defects, interstitials, polarizability, imperfection, defect centers, glass, epitaxy, sodium hydroxide, metallic substrate, crystallization, point, tip, susceptibility, ferroelectric, ordering, force, correlation, collective, shift, distortion, coalescence, crowdions, electrolysi

Expanded Phenotypic Diagnoses for 24 Recently Named New Taxa of Hesperiidae (Lepidoptera)

Expanded diagnoses by phenotypic characters for the 24 new taxa named in the article Genomes of skipper butterflies reveal extensive convergence of wing patterns by Li, W., Cong, Q., Shen, J., Zhang, J., Hallwachs, W., Janzen, D.H. and Grishin, N.V., 2019 and published in the Proceedings of the National Academy of Sciences of the United States of America on March 15, 2019 are provided and illustrated. More detailed diagnoses will help identifying these phylogenetic groups by their wing patterns and shapes and other morphological characters including the structures of antennae and genitalia using this single publication, instead of obtaining the sequences or inspecting additional works referenced in the original diagnoses for brevity

Nanomechanical morphology of amorphous, transition, and crystalline domains in phase change memory thin films

In the search for phase change materials (PCM) that may rival traditional random access memory, a complete understanding of the amorphous to crystalline phase transition is required. For the well-known Ge2Sb2Te5 (GST) and GeTe (GT) chalcogenides, which display nucleation and growth dominated crystallization kinetics, respectively, this work explores the nanomechanical morphology of amorphous and crystalline phases in 50 nm thin films. Subjecting these PCM specimens to a lateral thermal gradient spanning the crystallization temperature allows for a detailed morphological investigation. Surface and depth-dependent analyses of the resulting amorphous, transition and crystalline regions are achieved with shallow angle cross-sections, uniquely implemented with beam exit Ar ion polishing. To resolve the distinct phases, ultrasonic force microscopy (UFM) with simultaneous topography is implemented revealing a relative stiffness contrast between the amorphous and crystalline phases of 14% for the free film surface and 20% for the cross-sectioned surface. Nucleation is observed to occur preferentially at the PCM-substrate and free film interface for both GST and GT, while fine subsurface structures are found to be sputtering direction dependent. Combining surface and cross-section nanomechanical mapping in this manner allows 3D analysis of microstructure and defects with nanoscale lateral and depth resolution, applicable to a wide range of materials characterization studies where the detection of subtle variations in elastic modulus or stiffness are required

Mathematical modelling of the spread of contamination during fires in forests exposed to radioactive contamination

The paper suggested in the context of the general mathematical model of forest fires [1] gives a new mathematical setting and method of numerical solution of a problem of a radioactive spread above the forest region. Numerical solution of problems of radioactive smoke spread during crown fire in exemplified heat energy release in the forest fire front was found. Heat energy release in the forest fire front was found to cause further radioactive particles spread by the action of wind. In the absence of wind, radioactive smoke particles deposit again on the underlying surface after a time. As a wind velocity increases, these particles are transferred in the ground layer over distances proportional to a wind velocity

INFORMATION TECHNOLOGIES IN FORMATION OF SETTING OF A HEALTHY STUDENT'S LIFESTYLE

This article considered the instruments of influence on young people through various information technologies, and selected the best resource, with an impact on boys and girls aged 16 to 34. In addition there were an-alyzed a comprehensive approach to young people from the Federal Agency for Youth AffairsВ данной статье были рассмотрены инструменты воздействия на молодёжь с помощью различных информационных технологий, а также выбран наилучший ресурс, оказывающий воздействие на молодёжь. Кроме того, был проанализирован комплексный подход к молодым людям со стороны Федерального агентства по делам молодеж

Polarization bremsstrahlung by fast charge on atomic bound electrons—Analog of nuclear M¨ossbauer’s effect

Features of polarization bremsstrahlung radiation (PB) by a relativistic charge on medium electrons bound in atoms are discussed. PB is considered as a dispersion of virtual photons of an electromagnetic field of a fast charge on atomic bound electrons. In this case atomic electron can get dispersed at a recoil energy in only certain portions, as in the nuclear M¨ossbauer process. Because of this a spectrum of dispersed photons is degenerated in a series of narrow peaks