A general theorem on the divergence of vortex beams

The propagation and divergence properties of beams carrying orbital angular momentum (OAM) play a crucial role in many applications. Here we present a general study on the divergence of optical beams with OAM. We show that the mean absolute value of the OAM imposes a lower bound on the value of the beam divergence. We discuss our results for two different definitions of the divergence, the so called rms or encircled-energy. The bound on the rms divergence can be expressed as a generalized uncertainty principle, with applications in long-range communication, microscopy and 2D quantum systems.Comment: RevTex, published versio

Complete and Deterministic discrimination of polarization Bell state assisted by momentum entanglement

A complete and deterministic Bell state measurement was realized by a simple linear optics experimental scheme which adopts 2-photon polarization-momentum hyperentanglement. The scheme, which is based on the discrimination among the single photon Bell states of the hyperentangled state, requires the adoption of standard single photon detectors. The four polarization Bell states have been measured with average fidelity $F=0.889\pm0.010$ by using the linear momentum degree of freedom as the ancilla. The feasibility of the scheme has been characterized as a function of the purity of momentum entanglement.Comment: 4 pages, v2, comments adde

Dynamical correlation functions and the quantum Rabi model

We study the quantum Rabi model within the framework of the analytical solution developed in Phys. Rev. Lett. 107,100401 (2011). In particular, through time-dependent correlation functions, we give a quantitative criterion for classifying two regions of the quantum Rabi model, involving the Jaynes-Cummings, the ultrastrong, and deep strong coupling regimes. In addition, we find a stationary qubit-field entangled basis that governs the whole dynamics as the coupling strength overcomes the mode frequency.Comment: 8 pages, 8 figures. Revised version, accepted for publication in Physical Review

Evaluation of the vibrations transmitted to the hand-arm system in the use of portable harvesters for olives

The use of portable harvesters in olives harvesting is presently widely diffused in Sicily, south Italy, both to reduce the costs of production and to assure the olive oil quality. Nevertheless, it's well known that the use of such tools may involve risk of exposure to vibration transmitted to the hand-arm system which is a potential cause of muscular/skeletal pains, and specific pathologies such as Hand-Arm Vibration Syndrome (HAVS), Vibration-Induced White Finger (VWF) and Carpal Tunnel Syndrome (CTS). The aim of this study was to assess the level of exposure to vibration transmitted to the hand-arm system of the operators during the use of portable harvesters for olives. Two different commonly used types of tools were evaluated performing both laboratory and field tests. One was a hook type harvester provided with an internal combustion engine; the other an electric portable harvester consisting of a bar ending with a comb, equipped with an electric motor. The daily action value established by the European Directive 2002/44/EC was always considerably exceeded by the two harvesters for both hands both in the laboratory and in the field tests; however, the electric comb showed A(8) values about halved with respect to the hook type, equal to 20.79 and 18.69 m s-2 respectively for right and left hand in the field tests against 42.07 and 30.03 m s-2 obtained with the hook type harvester

Polarization entangled state measurement on a chip

The emerging strategy to overcome the limitations of bulk quantum optics consists of taking advantage of the robustness and compactness achievable by the integrated waveguide technology. Here we report the realization of a directional coupler, fabricated by femtosecond laser waveguide writing, acting as an integrated beam splitter able to support polarization encoded qubits. This maskless and single step technique allows to realize circular transverse waveguide profiles able to support the propagation of Gaussian modes with any polarization state. Using this device, we demonstrate the quantum interference with polarization entangled states and singlet state projection.Comment: Revtex, 5+2 pages (with supplementary information), 4+1 figure

Haemoglobin Engineering: For fun and money

AbstractThe recent transplantation of an unusual allosteric effect from crocodile to human haemoglobin has implications for both molecular evolution and the engineering of artificial blood substitutes

N=1 Super Yang-Mills Domain Walls via The Extended Veneziano Yankielowicz Theory

We investigate the vacuum structure of pure SU(N) N=1 super Yang-Mills. The theory is expected to possess N vacua with associated domain walls. We show that the newly extended version of the low energy effective Lagrangian for super Yang-Mills supports the BPS domain wall solutions associated with any two vacua aligned with the origin of the moduli space. For the two color theory the domain wall analysis is complete. We also find new non BPS domain wall solutions connecting any two vacua of the underling SU(N) super Yang-Mills theory not necessarely aligned. When two vacua are aligned with the origin of the moduli space these solutions are the BPS ones. We also discuss the generic BPS domain wall solutions connecting any two vacua within the extended Veneziano-Yankielowicz theory.Comment: 25 pages, 5 figures plain Late

Trench width dependant deeply etched surface-defined InP gratings for low-cost high speed DFB/DBR

In this paper we are reporting a fabrication process for multi-section telecom lasers based on surface defined lateral gratings, which is compatible with low-cost high-throughput nano-imprint lithography. A new grating definition process is developed, which allow a better control of the cross section geometry to obtain higher coupling strength

Effects of Force Level and Hand Dominance on Bilateral Transfer of a Fine Motor Skill

Our research is about bilateral transfer, a concept in motor learning where skills learned by one limb are "transferred", allowing the opposite limb to benefit from what was learned by the first limb. Previous research into bilateral transfer has raised questions about whether specific aspects of motor coordination are or are not transferred. We wanted to see whether learning to control pinch force by the thumb and index finger is transferable, and if it is, whether the learning transfers equally from either hand. We also want to look into the effects of different force levels on the degree of transfer. We designed a task using a program that takes force levels as inputs and has the participant trace shapes on a screen. By having participants perform with one hand, then practice with the other, and finally perform again with the initial hand, we can measure transfer as the difference in performance before and after practice with the other hand.Kinesiology and Health Educatio

One-way quantum computation via manipulation of polarization and momentum qubits in two-photon cluster states

Four-qubit cluster states of two photons entangled in polarization and linear momentum have been used to realize a complete set of single qubit rotations and the C-NOT gate for equatorial qubits with high values of fidelity. By the computational equivalence of the two degrees of freedom our result demonstrate the suitability of two photon cluster states for rapid and efficient one-way quantum computing.Comment: RevTex4, 4 pages, 3 figure