8,384 research outputs found

    Nondestructive Measurement of Orbital Angular Momentum for an Electron Beam

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    Free electrons with a helical phase front, referred to as "twisted" electrons, possess an orbital angular momentum (OAM) and, hence, a quantized magnetic dipole moment along their propagation direction. This intrinsic magnetic moment can be used to probe material properties. Twisted electrons thus have numerous potential applications in materials science. Measuring this quantity often relies on a series of projective measurements that subsequently change the OAM carried by the electrons. In this Letter, we propose a nondestructive way of measuring an electron beam's OAM through the interaction of this associated magnetic dipole with a conductive loop. Such an interaction results in the generation of induced currents within the loop, which are found to be directly proportional to the electron's OAM value. Moreover, the electron experiences no OAM variations and only minimal energy losses upon the measurement, and, hence, the nondestructive nature of the proposed technique.Comment: 5 pages, 3 figures, and supplemental material that is comprised of text and 4 figure

    The optical M\"{o}bius strip cavity: Tailoring geometric phases and far fields

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    The M\"{o}bius strip, a long sheet of paper whose ends are glued together after a 180∘180^{\circ} twist, has remarkable geometric and topological properties. Here, we consider dielectric M\"{o}bius strips of finite width and investigate the interplay between geometric properties and resonant light propagation. We show how the polarization dynamics of the electromagnetic wave depends on the topological properties, and demonstrate how the geometric phase can be manipulated between 00 and π\pi through the system geometry. The loss of the M\"{o}bius character in thick cavities and for small twist segment lengths allows one to manipulate the polarization dynamics and the far-field emission, and opens the venue for applications.Comment: 6 pages, 5 figure

    Controlled parity switch of persistent currents in quantum ladders

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    We investigate the behavior of persistent currents for a fixed number of noninteracting fermions in a periodic quantum ladder threaded by Aharonov-Bohm and transverse magnetic fluxes Φ\Phi and χ\chi. We show that the coupling between ladder legs provides a way to effectively change the ground-state fermion-number parity, by varying χ\chi. Specifically, we demonstrate that varying χ\chi by 2π2\pi (one flux quantum) leads to an apparent fermion-number parity switch. We find that persistent currents exhibit a robust 4π4\pi periodicity as a function of χ\chi, despite the fact that χ→χ+2π\chi \to \chi + 2\pi leads to modifications of order 1/N1/N of the energy spectrum, where NN is the number of sites in each ladder leg. We show that these parity-switch and 4π4\pi periodicity effects are robust with respect to temperature and disorder, and outline potential physical realizations using cold atomic gases and, for bosonic analogs of the effects, photonic lattices.Comment: 5 pages, 4 figures + Supplemental Materia

    Construction and Assembly of the Wire Planes for the MicroBooNE Time Projection Chamber

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    In this paper we describe how the readout planes for the MicroBooNE Time Projection Chamber were constructed, assembled and installed. We present the individual wire preparation using semi-automatic winding machines and the assembly of wire carrier boards. The details of the wire installation on the detector frame and the tensioning of the wires are given. A strict quality assurance plan ensured the integrity of the readout planes. The different tests performed at all stages of construction and installation provided crucial information to achieve the successful realisation of the MicroBooNE wire planes.Comment: 24 pages, 22 figures, accepted for publication as Technical Report in JINS

    Conceptual design and feasibility evaluation model of a 10 to the 8th power bit oligatomic mass memory. Volume 2: Feasibility evaluation model

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    The partially populated oligatomic mass memory feasibility model is described and evaluated. A system was desired to verify the feasibility of the oligatomic (mirror) memory approach as applicable to large scale solid state mass memories

    Laser angle sensor development

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    Electrical and optical parameters were developed for a two axis (pitch/roll) laser angle sensor. The laser source and detector were mounted in the plenum above the model. Two axis optical distortion measurements of flow characteristics in a 0.3 transonic cryogenic tunnel were made with a shearing interferometer. The measurement results provide a basis for estimating the optical parameters of the laser angle sensor. Experimental and analytical information was generated on model windows to cover the reflector. A two axis breadboard was assembled to evaluate different measurement concepts. The measurement results were used to develop a preliminary design of a laser angle sensor. Schematics and expected performance specifications are included

    Adiabatic Approach for Low-Power Passive Near Field Communication Systems

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    This thesis tackles the need of ultra-low power electronics in the power limited passive Near Field Communication (NFC) systems. One of the techniques that has proven the potential of delivering low power operation is the Adiabatic Logic Technique. However, the low power benefits of the adiabatic circuits come with the challenges due to the absence of single opinion on the most energy efficient adiabatic logic family which constitute appropriate trade-offs between computation time, area and complexity based on the circuit and the power-clocking schemes. Therefore, five energy efficient adiabatic logic families working in single-phase, 2-phase and 4-phase power-clocking schemes were chosen. Since flip-flops are the basic building blocks of any sequential circuit and the existing flip-flops are MUX-based (having more transistors) design, therefore a novel single-phase, 2-phase and 4-phase reset based flip-flops were proposed. The performance of the multi-phase adiabatic families was evaluated and compared based on the design examples such as 2-bit ring counter, 3-bit Up-Down counter and 16-bit Cyclic Redundancy Check (CRC) circuit (benchmark circuit) based on ISO 14443-3A standard. Several trade-offs, design rules, and an appropriate range for the supply voltage scaling for multi-phase adiabatic logic are proposed. Furthermore, based on the NFC standard (ISO 14443-3A), data is frequently encoded using Manchester coding technique before transmitting it to the reader. Therefore, if Manchester encoding can be implemented using adiabatic logic technique, energy benefits are expected. However, adiabatic implementation of Manchester encoding presents a challenge. Therefore, a novel method for implementing Manchester encoding using adiabatic logic is proposed overcoming the challenges arising due to the AC power-clock. Other challenges that come with the dynamic nature of the adiabatic gates and the complexity of the 4-phase power-clocking scheme is in synchronizing the power-clock v phases and the time spent in designing, validation and debugging of errors. This requires a specific modelling approach to describe the adiabatic logic behaviour at the higher level of abstraction. However, describing adiabatic logic behaviour using Hardware Description Languages (HDLs) is a challenging problem due to the requirement of modelling the AC power-clock and the dual-rail inputs and outputs. Therefore, a VHDL-based modelling approach for the 4-phase adiabatic logic technique is developed for functional simulation, precise timing analysis and as an improvement over the previously described approaches

    Measurement technology: A compilation

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    Technical information is presented on measurement techniques and instruments, measurement applications for inspection activities, measurement sensors, and data conversion methods. Photographs or diagrams are included for each instrument or method described, and where applicable, patent information is given
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