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

Spectral analysis of Floating Car Data

Floating Car Data (FCD) are one important data source in traffic telematic systems. The original variable in these systems is the vehicle velocity. The paper analyses the measured value “vehicle velocity&quot; by methods of information technology. Consequences for processing, transmission and storage of FCD under condition of limited resources are discussed.</p><p style=&quot;line-height: 20px;&quot;> Starting point of the investigation is the analysis of spectral characteristics of velocity-time-profiles. The spectra are determined by the Discrete Fourier Transform (DFT) from measurement data and simulation data of a microscopic traffic model. One essential property of velocity-time-profiles is their low-pass characteristic. The resulting cut-off-frequency is comparatively small and depends on the traffic scenario. Conclusions concerning the necessary sample rate in FCD systems and the processing of raw data are discussed. Finally the transinformation of velocity-time-profiles is analysed. This results in similar values for an optimal sample rate of FCD systems under condition of limited transmission capacity

Strength and fracture of Si micropillars: A new scanning electron microscopy-based micro-compression test

A novel method for in situ scanning electron microscope (SEM) micro-compression tests is presented. The direct SEM observation during the instrumented compression testing allows for very efficient positioning and assessment of the failure mechanism. Compression tests on micromachined Si pillars with volumes down to 2 μm3 are performed inside the SEM, and the results demonstrate the potential of the method. In situ observation shows that small diameter pillars tend to buckle while larger ones tend to crack before failure. Compressive strength increases with decreasing pillar diameter and reaches almost 9 GPa for submicrometer diameter pillars. This result is in agreement with earlier bending experiments on Si. Difficulties associated with precise strain measurements are discusse

Linear optics implementation of general two-photon projective measurement

We will present a method of implementation of general projective measurement of two-photon polarization state with the use of linear optics elements only. The scheme presented succeeds with a probability of at least 1/16. For some specific measurements, (e.g. parity measurement) this probability reaches 1/4.Comment: 8 page

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

Generation of correlated photons in controlled spatial modes by down-conversion in nonlinear waveguides

We report the observation of correlated photon pairs generated by spontaneous parametric down-conversion in a quasi-phase matched KTiOPO4 nonlinear waveguide. The highest ratio of coincidence to single photon count rates observed in the 830 nm wavelength region exceeds 18%. This makes nonlinear waveguides a promising source of correlated photons for metrology and quantum information processing applications. We also discuss possibilities of controlling the spatial characteristics of the down-converted photons produced in multimode waveguide structures.Comment: 4 pages, REVTe

Single-particle nonlocality and entanglement with the vacuum

We propose a single-particle experiment that is equivalent to the conventional two-particle experiment used to demonstrate a violation of Bell's inequalities. Hence, we argue that quantum mechanical nonlocality can be demonstrated by single-particle states. The validity of such a claim has been discussed in the literature, but without reaching a clear consensus. We show that the disagreement can be traced to what part of the total state of the experiment one assigns to the (macroscopic) measurement apparatus. However, with a conventional and legitimate interpretation of the measurement process one is led to the conclusion that even a single particle can show nonlocal properties.Comment: 6 pages, 5 figure

Probabilistic Quantum Logic Operations Using Polarizing Beam Splitters

It has previously been shown that probabilistic quantum logic operations can be performed using linear optical elements, additional photons (ancilla), and post-selection based on the output of single-photon detectors. Here we describe the operation of several quantum logic operations of an elementary nature, including a quantum parity check and a quantum encoder, and we show how they can be combined to implement a controlled-NOT (CNOT) gate. All of these gates can be constructed using polarizing beam splitters that completely transmit one state of polarization and totally reflect the orthogonal state of polarization, which allows a simple explanation of each operation. We also describe a polarizing beam splitter implementation of a CNOT gate that is closely analogous to the quantum teleportation technique previously suggested by Gottesman and Chuang [Nature 402, p.390 (1999)]. Finally, our approach has the interesting feature that it makes practical use of a quantum-eraser technique.Comment: 9 pages, RevTex; Submitted to Phys. Rev. A; additional references inlcude

Variable temperature ultra-nanoindentation system: Elevated and cryogenic temperature measurements

One of the primary motivations for development of instrumented indentation was to measure the mechanical properties of thin films. Characterization of thin film mechanical properties as a function of temperature is of immense industrial and scientific interest. The major bottlenecks in variable temperature measurements have been thermal drift, signal stability (noise) and oxidation of/condensation on the surface. Thermal drift is a measurement artifact that arises due to thermal expansion/contraction of indenter tip and loading column. This gets superimposed on the mechanical behavior data precluding accurate extraction of mechanical properties of the sample at elevated/cryogenic temperatures [1]. Reliable load-displacement measurements up to 700 °C have additional technical requirements including a differential displacement measurement system, independent tip and sample heating and active thermal management of the system as well as answers to scientific questions like the temperature in the contact area or the tip wear. It is then mandatory to have a suitable device for exploring such scientific limits to technical goals and understanding nanoscale high temperature deformation and fracture. Such a device must be able to maintain the thermal drift below 0.1 nm/sec, and should be implemented in a robust system which minimizes noise (electrical, vibrational, thermal, etc..), with a continuous correction based on active top- referencing. A novel vacuum nanoindentation system that can perform reliable load-displacement measurements over a wide temperature range (-150 to 700 °C) will be presented. This system is based on the Ultra Nanoindentation Tester (UNHT [2], [3]) that utilizes an active surface referencing technique comprising of two independent axes, one for surface referencing and another for indentation. This results in negligible compliance of the system and very low thermal drift rates. Vacuum is essential to prevent sample/tip oxidation at elevated temperatures and condensation at cryogenic temperatures. The sample, indenter and reference tip are heated separately and the surface temperatures matched establishing an Infrared bath to obtain drift rates as low as 5nm/min at 700 °C. Instrumentation development, system characterization, experimental protocol, operational refinements and thermal drift characteristics at various temperatures will be presented. The system was validated by performing extensive testing on calibration materials like fused silica and single crystal aluminum. Case studies on elevated temperature properties of P91 and 316L steels and low temperature properties of nanocrystalline nickel and copper will be presented. Finally, the current status and future roadmap for variable temperature nanoindentation testing will be discussed