Loss of quantum coherence due to non-stationary glass fluctuations

Low-temperature dynamics of insulating glasses is dominated by a macroscopic concentration of tunneling two-level systems (TTLS). The distribution of the switching/relaxation rates of TTLS is exponentially broad, which results in non-equilibrium state of the glass at arbitrarily long time-scales. Due to the electric dipolar nature, the switching TTLS generate fluctuating electromagnetic fields. We study the effect of the non-thermal slow fluctuators on the dephasing of a solid state qubit. We find that at low enough temperatures, non-stationary contribution can dominate the stationary (thermal) one, and discuss how this effect can be minimized.Comment: 4 page

Zero-bias anomalies of point contact resistance due to adiabatic electron renormalization of dynamical defects

We study effect of the adiabatic electron renormalization on the parameters of the dynamical defects in the ballistic metallic point contact. The upper energy states of the ``dressed'' defect are shown to give a smaller contribution to a resistance of the contact than the lower energy ones. This holds both for the "classical" renormalization related to defect coupling with average local electron density and for the "mesoscopic" renormalization caused by the mesoscopic fluctuations of electronic density the dynamical defects are coupled with. In the case of mesoscopic renormalization one may treat the dynamical defect as coupled with Friedel oscillations originated by the other defects, both static and mobile. Such coupling lifts the energy degeneracy of the states of the dynamical defects giving different mesoscopic contribution to resistance, and provides a new model for the fluctuator as for the object originated by the electronic mesoscopic disorder rather than by the structural one. The correlation between the defect energy and the defect contribution to the resistance leads to zero-temperature and zero-bias anomalies of the point contact resistance. A comparison of these anomalies with those predicted by the Two Channel Kondo Model (TCKM) is made. It is shown, that although the proposed model is based on a completely different from TCKM physical background, it leads to a zero-bias anomalies of the point contact resistance, which are qualitatively similar to TCKM predictions.Comment: 6 pages, to be published in Phys. Rev.

ЛІНГВОСТИЛІСТИЧНІ ОСОБЛИВОСТІ АНГЛІЙСЬКОЇ ПІСНІ ЯК ТЕКСТУ МАЛОЇ ФОРМИ. (Linguistical and stylistical peculiarities of the English song as a text of small form.)

Стаття присвячена дослідженню лінгвостилістичних особливостей англомовної пісні як тексту малої форми і зумовлена спрямуванням сучасних лінгвістичних досліджень на поглиблення дослідницької парадигми лінгвістики тексту новим знанням про механізми систематизації структурних, функціональних та лінгвальних ознак тексту взагалі та його малої форми зокрема. (The article deals with the study of linguostylistic peculiarities of English songs. It is stipulated by the interest of modern linguistic investigations in deepening the research paradigm of text linguistics with new knowledge about the mechanisms of systematization of structural, functional and linguistic features of the text in general and short texts in particular.

Low-frequency noise in tunneling through a single spin

We propose measurements of low-frequency noise in the tunneling current through a single molecule with a spin as an experimental probe for identifying a mechanism of the spin-dependent tunneling. A specific tail near the zero frequency in the noise spectrum is predicted; the amplitude and the width of being of the same order of magnitude as the recently reported peak in the noise spectrum at the spin Larmor frequency. The ratio of the spectrum amplitudes at zero- and Larmor frequencies is shown to be a convenient tool for testing theoretical predictions.Comment: 4 pages, 3 figures. In the replaced version some mistakes are fixe

Josephson transport through a Hubbard impurity center

We investigate the Josephson transport through a thin semiconductor barrier containing impurity centers with the on-site Hubbard interaction $u$ of an arbitrary sign and strength. We find that in the case of the repulsive interaction the Josephson current changes sign with the temperature increase if the energy of the impurity level $\epsilon$ (measured from the Fermi energy of superconductors) falls in the interval $(-u,0)$. We predict strong temporal fluctuations of the current if only a few centers present within the junction. In the case of the attractive impurity potential ($u<0$) and at low temperatures, the model is reduced to the effective two level Hamiltonian allowing thus a simple description of the nonstationary Josephson effect in terms of pair tunneling processes

Improvement of forms and methods of teaching in higher education

Розглянуто поняття форм і методів навчання у вищому навчальному закладі як складових компонентів авторських педагогічних систем та розглянуто їх характеристику. Виділено організаційні форми навчання, які одночасно є способами безперервного управління пізнавальною діяльністю студентів. До них відносять: лекції, семінарські заняття, лабораторні роботи, практикуми, самостійну роботу, науково-дослідну роботу студентів, різного виду практику тощо. Показано, що ефективність навчання безпосередньо залежить від форм і методів, які викладач буде використовувати в навчально-виховному процесі. Вміле їх поєднання дозволить активізувати студента і викликати в ньому інтерес до процесу навчання.The concepts of forms and methods of teaching in higher education as constituent components of the author's pedagogical systems were considered and their characteristics were considered too. Organizational forms of education were given. They are method of continuous management of cognitive activity of the students. These include: lectures, seminars, laboratory works, self-work, research work of students, various types of practice, etc. It is shown that the effectiveness of teaching depends directly on the forms and methods that the teacher will use in the educational process. Skillful combination of them will allow activating the student and arouse interest in him in the learning process

Zero-bias anomalies on Sr0.88_{0.88}La0.12_{0.12}CuO2_2 thin films

High-impedance contacts made on the surface of Sr$_{0.88}$La$_{0.12}$CuO$_2$ superconducting thin films systematically display a zero-bias anomaly. We consider two-level systems (TLS) as the origin of this anomaly. We observe that the contribution of some TLS to the contact resistance is weakened by a magnetic field. We show that this could result from the increase of the TLS relaxation rate in the superconducting state, due to its ability to create pairs of quasiparticles out of the condensate, when located close to the surface of the film