Mass Density of Individual Cobalt Nanowires

The mass density of nanowires is determined using in-situ resonance frequency experiments combined with quasi-static nanotensile tests. Our results reveal a mass density of 7.36 g/cm3 on average which is below the theoretical density of bulk cobalt. Also the density of electrodeposited cobalt nanowires is found to decrease with the aspect ratio. The results are discussed in terms of the measurement accuracy and the microstructure of the nanowires.Comment: 3 Figure

Optical readout of charge and spin in a self-assembled quantum dot in a strong magnetic field

We present a theory and experiment demonstrating optical readout of charge and spin in a single InAs/GaAs self-assembled quantum dot. By applying a magnetic field we create the filling factor 2 quantum Hall singlet phase of the charged exciton. Increasing or decreasing the magnetic field leads to electronic spin-flip transitions and increasing spin polarization. The increasing total spin of electrons appears as a manifold of closely spaced emission lines, while spin flips appear as discontinuities of emission lines. The number of multiplets and discontinuities measures the number of carriers and their spin. We present a complete analysis of the emission spectrum of a single quantum dot with N=4 electrons and a single hole, calculated and measured in magnetic fields up to 23 Tesla.Comment: 9 pages, 3 figures, submitted to Europhysics Letter

Dephasing of Mollow Triplet Sideband Emission of a Resonantly Driven Quantum Dot in a Microcavity

Detailed properties of resonance fluorescence from a single quantum dot in a micropillar cavity are investigated, with particular focus on emission coherence in dependence on optical driving field power and detuning. Power-dependent series over a wide range could trace characteristic Mollow triplet spectra with large Rabi splittings of $|\Omega| \leq 15$ GHz. In particular, the effect of dephasing in terms of systematic spectral broadening $\propto \Omega^2$ of the Mollow sidebands is observed as a strong fingerprint of excitation-induced dephasing. Our results are in excellent agreement with predictions of a recently presented model on phonon-dressed QD Mollow triplet emission in the cavity-QED regime

Phonon-Assisted Incoherent Excitation of a Quantum Dot and its Emission Properties

We present a detailed study of a phonon-assisted incoherent excitation mechanism of single quantum dots. A spectrally-detuned laser couples to a quantum dot transition by mediation of acoustic phonons, whereby excitation efficiencies up to 20 % with respect to strictly resonant excitation can be achieved at T = 9 K. Laser frequency-dependent analysis of the quantum dot intensity distinctly maps the underlying acoustic phonon bath and shows good agreement with our polaron master equation theory. An analytical solution for the photoluminescence is introduced which predicts a broadband incoherent coupling process when electron-phonon scattering is in the strong phonon coupling (polaronic) regime. Additionally, we investigate the coherence properties of the emitted light and study the impact of the relevant pump and phonon bath parameters

Анализ и моделирование макроэкономических процессов в переходной период

Рассматривается построение моделей процессов инфляции и трансформирования отношений собственности. На основании разработанных моделей поставлены задачи оптимального управления данными процессами, для решения которых применяется метод динамического моделирования. Получены аналитические выражения для оптимальных управляющих воздействий и оптимальные траектории реализации процессов инфляции и трансформирования отношений собственности.У статті розглядається побудова моделей процесів інфляції і трансформування власності. На підставі розроблених моделей поставлені задачі оптимального керування даними процесами, для рішення яких застосовується метод динамічного моделювання. Отримані аналітичні співвідношення для оптимальних керуючих впливів і оптимальні траєкторії реалізації процесів інфляції і трансформування власності.The paper is devoted to construction of mathematical models for inflation and transforming the property form or privatization. The models constructed are used for the optimal control problem statement aiming to compute optimal trajectories for the processes implementation. To solve the optimal control problem dynamic programming method is applied. As a result of the problem solving analytical expressions were derived for optimal inputs, and respective optimal trajectories were computed for various initial conditions

Quantum filter for non-local polarization properties of photonic qubits

We present an optical filter that transmits photon pairs only if they share the same horizontal or vertical polarization, without decreasing the quantum coherence between these two possibilities. Various applications for entanglement manipulations and multi-photon qubits are discussed.Comment: 7 pages, including one figure, short discussion of error sources adde