Nonideal quantum detectors in Bayesian formalism

The Bayesian formalism for a continuous measurement of solid-state qubits is derived for a model which takes into account several factors of the detector nonideality. In particular, we consider additional classical output and backaction noises (with finite correlation), together with quantum-limited output and backaction noises, and take into account possible asymmetry of the detector coupling. The formalism is first derived for a single qubit and then generalized to the measurement of entangled qubits.Comment: 10 page

Enhanced shot noise in resonant tunnelling via interacting localised states

In a variety of mesoscopic systems shot noise is seen to be suppressed in comparison with its Poisson value. In this work we observe a considerable enhancement of shot noise in the case of resonant tunnelling via localised states. We present a model of correlated transport through two localised states which provides both a qualitative and quantitative description of this effect.Comment: 4 pages, 4 figure

Nonequilibrium spin distribution in single-electron transistor

Single-electron transistor with ferromagnetic outer electrodes and nonmagnetic island is studied theoretically. Nonequilibrium electron spin distribution in the island is caused by tunneling current. The dependencies of the magnetoresistance ratio $\delta$ on the bias and gate voltages show the dips which are directly related to the induced separation of Fermi levels for electrons with different spins. Inside a dip $\delta$ can become negative.Comment: 11 pages, 2 eps figure

Legal protection of life and health of a child: interbranch problems

The current study considered the problems of legal protection of a child’s life and health before and after birth, analyzed Russian and foreign legislation, it was proposed to consolidate the fundamental principles of international law in the legislation of Russian Federation, and it was provided the human embryo protectio

Протидія торгівлі людьми в інформаційній сфері

Коротков І. С. Протидія торгівлі людьми в інформаційній сфері / І. С. Коротков // Протидія кіберзагрозам та торгівлі людьми: зб. матеріалів Міжнар. наук.-практ. конф. (м. Харків, 26 листоп. 2019 р.) / МВС України, Харків. нац. ун-т внутр. справ ; Координатор проектів ОБСЄ в Україні. – Харків : ХНУВС, 2019. – С. 99-100.Зазначено, що торгівля людьми залишається проблемою людства, для протидії цьому в статті пропонуються такі заходи: 1) посилити відповідальність за такі види злочинів; 2) зменшити кількість часу на оформлення документів, відсутність яких не дозволяє правоохоронцям своєчасно заарештувати, чи викрити злочин; 3) блокувати сайти, які мають хоч якийсь стосунок до ескорт-послуг чи інших сайтів, які порушують законодавство.It is noted that human trafficking remains a problem of mankind, to counteract this, the article proposes the following measures: 1) increase responsibility for the following types of crimes; 2) reduce the amount of time for paperwork, the absence of which does not allow law enforcement officers to arrest or expose the crime in a timely manner; 3) block sites that have anything to do with escort services or other sites that violate the law.Отмечено, что торговля людьми остается проблемой человечества, для противодействия этому в статье предлагаются следующие меры: 1) усилить ответственность за такие виды преступлений; 2) уменьшить количество времени на оформление документов, отсутствие которых не разрешает правоохранителям своевременно арестовать или разоблачить преступление; 3) блокировать сайты, имеющие хоть какое-то отношение к эскорт-услугам или другим сайтам, нарушающим законодательство

Measurement induced quantum-classical transition

A model of an electrical point contact coupled to a mechanical system (oscillator) is studied to simulate the dephasing effect of measurement on a quantum system. The problem is solved at zero temperature under conditions of strong non-equilibrium in the measurement apparatus. For linear coupling between the oscillator and tunneling electrons, it is found that the oscillator dynamics becomes damped, with the effective temperature determined by the voltage drop across the junction. It is demonstrated that both the quantum heating and the quantum damping of the oscillator manifest themselves in the current-voltage characteristic of the point contact.Comment: in RevTex, 1 figure, corrected notatio

A Numerical Study of Transport and Shot Noise at 2D Hopping

We have used modern supercomputer facilities to carry out extensive Monte Carlo simulations of 2D hopping (at negligible Coulomb interaction) in conductors with the completely random distribution of localized sites in both space and energy, within a broad range of the applied electric field $E$ and temperature $T$, both within and beyond the variable-range hopping region. The calculated properties include not only dc current and statistics of localized site occupation and hop lengths, but also the current fluctuation spectrum. Within the calculation accuracy, the model does not exhibit $1/f$ noise, so that the low-frequency noise at low temperatures may be characterized by the Fano factor $F$. For sufficiently large samples, $F$ scales with conductor length $L$ as $(L_c/L)^{\alpha}$, where $\alpha=0.76\pm 0.08 < 1$, and parameter $L_c$ is interpreted as the average percolation cluster length. At relatively low $E$, the electric field dependence of parameter $L_c$ is compatible with the law $L_c\propto E^{-0.911}$ which follows from directed percolation theory arguments.Comment: 17 pages, 8 figures; Fixed minor typos and updated reference

Localization and Capacitance Fluctuations in Disordered Au Nano-junctions

Nano-junctions, containing atomic-scale gold contacts between strongly disordered leads, exhibit different transport properties at room temperature and at low temperature. At room temperature, the nano-junctions exhibit conductance quantization effects. At low temperatures, the contacts exhibit Coulomb-Blockade. We show that the differences between the room-temperature and low temperature properties arise from the localization of electronic states in the leads. The charging energy and capacitance of the nano-junctions exhibit strong fluctuations with applied magnetic field at low temperature, as predicted theoretically.Comment: 20 pages 8 figure