A nanomechanical resonator shuttling single electrons at radio frequencies

We observe transport of electrons through a metallic island on the tip of a nanomechanical pendulum. The resulting tunneling current shows distinct features corresponding to the discrete mechanical eigenfrequencies of the pendulum. We report on measurements covering the temperature range from 300 K down to 4.2 K. We explain the I-V curve, which differs from previous theoretical predictions, with model calculations based on a Master equation approach.Comment: 5 pages, 4 jpeg-figure

Swapping and entangling hyperfine coupled nuclear spin baths

We numerically study the hyperfine induced nuclear spin dynamics in a system of two coupled quantum dots in zero magnetic field. Each of the electron spins is considered to interact with an individual bath of nuclear spins via homogeneous coupling constants (all coupling coefficients being equal). In order to lower the dimension of the problem, the two baths are approximated by two single long spins. We demonstrate that the hyperfine interaction enables to utilize the nuclear baths for quantum information purposes. In particular, we show that it is possible to swap the nuclear ensembles on time scales of seconds and indicate that it might even be possible to fully entangle them. As a key result, it turns out that the larger the baths are, the more useful they become as a resource of quantum information. Interestingly, the nuclear spin dynamics strongly benefits from combining two quantum dots of different geometry to a double dot set up.Comment: 6 pages, 7 figure

State of the Surface of Antibacterial Copper in Phosphate Buffered Saline

The state was investigated of the copper surface in phosphate buffered saline (PBS; 140 mM Cl-, 10 mM phosphate; pH 7) by a combination of cyclic voltammetry (CV) and chronoamperometry (CA) with in situ spectroscopic ellipsometry and Raman spectroscopy. After polarization, samples were analyzed ex situ. In agreement with expectations on the basis of the Pourbaix diagram, Cu2O and Cu4O3 were observed when polarizing the system above approximate to-0.05 V vs. Ag vertical bar AgCl vertical bar 3M KCl. The formation of Cu2O did not lead to a passivation of the system. Rather, the system dissolved under formation of soluble square planar CuCl42-, identified by its strong Raman peak approximate to 300 cm(-1). During dissolution, spectroscopic ellipsometry showed a film with a stable steady state thickness. Energy electron loss spectroscopy (EELS) analysis of a cross section of the oxide after removal from the electrolyte showed that the oxide was Cu2O. It is suggested that Cl-replaces oxygen vacancies in the oxide layer. As soon as oxidation to Cu-II becomes dominant, the dissolution proceeds to soluble CuII species. The outer surface of copper under these conditions is hence a Cu2O-like surface, with CuII complexes present in solution. (C) The Author(s) 2017. Published by ECS. All rights reserved

State of the Surface of Antibacterial Copper in Phosphate Buffered Saline

The state was investigated of the copper surface in phosphate buffered saline (PBS; 140 mM Cl-, 10 mM phosphate; pH 7) by a combination of cyclic voltammetry (CV) and chronoamperometry (CA) with in situ spectroscopic ellipsometry and Raman spectroscopy. After polarization, samples were analyzed ex situ. In agreement with expectations on the basis of the Pourbaix diagram, Cu2O and Cu4O3 were observed when polarizing the system above approximate to-0.05 V vs. Ag vertical bar AgCl vertical bar 3M KCl. The formation of Cu2O did not lead to a passivation of the system. Rather, the system dissolved under formation of soluble square planar CuCl42-, identified by its strong Raman peak approximate to 300 cm(-1). During dissolution, spectroscopic ellipsometry showed a film with a stable steady state thickness. Energy electron loss spectroscopy (EELS) analysis of a cross section of the oxide after removal from the electrolyte showed that the oxide was Cu2O. It is suggested that Cl-replaces oxygen vacancies in the oxide layer. As soon as oxidation to Cu-II becomes dominant, the dissolution proceeds to soluble CuII species. The outer surface of copper under these conditions is hence a Cu2O-like surface, with CuII complexes present in solution. (C) The Author(s) 2017. Published by ECS. All rights reserved

Investigation of the crystallization process of CSD-ErBCO on IBAD-substrate via DSD approach

REBa$_{2}$Cu$_{3}$O$_{7-δ}$ (REBCO, RE: rare earth, such as Y and Gd) compounds have been extensively studied as a superconducting layer in coated conductors. Although ErBCO potentially has better superconducting properties than YBCO and GdBCO, little research has been made on it, especially in chemical solution deposition (CSD). In this work, ErBCO films were deposited on IBAD (ion-beam-assisted-deposition) substrates by CSD with low-fluorine solutions. The crystallization process was optimized to achieve the highest self-field critical current density (J$_{c}$) at 77 K. Commonly, for the investigation of a CSD process involving numerous process factors, one factor is changed keeping the others constant, requiring much time and cost. For more efficient investigation, this study adopted a novel design-of-experiment technique, definitive screening design (DSD), for the first time in CSD process. Two different types of solutions containing Er-propionate or Er-acetate were used to make two types of samples, Er-P and Er-A, respectively. Within the investigated range, we found that crystallization temperature, dew point, and oxygen partial pressure play a key role in Er-P, while the former two factors are significant for Er-A. DSD revealed these significant factors among six process factors with only 14 trials. Moreover, the DSD approach allowed us to create models that predict J$_{c}$ accurately. These models revealed the optimum conditions giving the highest J$_{c}$ values of 3.6 MA/cm$^{2}$ for Er-P and 3.0 MA/cm$^{2}$ for Er-A. These results indicate that DSD is an attractive approach to optimize CSD process

Quantum Effects in the Mechanical Properties of Suspended Nanomechanical Systems

We explore the quantum aspects of an elastic bar supported at both ends and subject to compression. If strain rather than stress is held fixed, the system remains stable beyond the buckling instability, supporting two potential minima. The classical equilibrium transverse displacement is analogous to a Ginsburg-Landau order parameter, with strain playing the role of temperature. We calculate the quantum fluctuations about the classical value as a function of strain. Excitation energies and quantum fluctuation amplitudes are compared for silicon beams and carbon nanotubes.Comment: RevTeX4. 5 pages, 3 eps figures. Submitted to Physical Review Letter

Form factors and photoproduction amplitudes

We examine the use of phenomenological form factors in tree level amplitudes for meson photoproduction. Two common recipes are shown to be fundamentally incorrect. An alternate form consistent with gauge invariance and crossing symmetry is proposed.Comment: To be published in PR

Entanglement and decoherence of a micromechanical resonator via coupling to a Cooper box

We analyse the quantum dynamics of a micromechanical resonator capacitively coupled to a Cooper box. With appropriate quantum state control of the Cooper box, the resonator can be driven into a superposition of spatially separated states. The Cooper box can also be used to probe the environmentally-induced decoherence of the resonator superposition state.Comment: 4 pages, 3 figure

Higher-order Abel equations: Lagrangian formalism, first integrals and Darboux polynomials

A geometric approach is used to study a family of higher-order nonlinear Abel equations. The inverse problem of the Lagrangian dynamics is studied in the particular case of the second-order Abel equation and the existence of two alternative Lagrangian formulations is proved, both Lagrangians being of a non-natural class (neither potential nor kinetic term). These higher-order Abel equations are studied by means of their Darboux polynomials and Jacobi multipliers. In all the cases a family of constants of the motion is explicitly obtained. The general n-dimensional case is also studied