GHZ-type and W-type entangled coherent states: generation and Bell-type inequality tests without photon counting

We study GHZ-type and W-type three-mode entangled coherent states. Both the types of entangled coherent states violate Mermin's version of the Bell inequality with threshold photon detection (i.e., without photon counting). Such an experiment can be performed using linear optics elements and threshold detectors with significant Bell violations for GHZ-type entangled coherent states. However, to demonstrate Bell-type inequality violations for W-type entangled coherent states, additional nonlinear interactions are needed. We also propose an optical scheme to generate W-type entangled coherent states in free-traveling optical fields. The required resources for the generation are a single-photon source, a coherent state source, beam splitters, phase shifters, photodetectors, and Kerr nonlinearities. Our scheme does not necessarily require strong Kerr nonlinear interactions, i.e., weak nonlinearities can be used for the generation of the W-type entangled coherent states. Furthermore, it is also robust against inefficiencies of the single-photon source and the photon detectors.Comment: 8 pages, 5 figures, to be published in Phys. Rev.

Accessible quantification of multiparticle entanglement

Entanglement is a key ingredient for quantum technologies and a fundamental signature of quantumness in a broad range of phenomena encompassing many-body physics, thermodynamics, cosmology and life sciences. For arbitrary multiparticle systems, entanglement quantification typically involves nontrivial optimisation problems, and it may require demanding tomographical techniques. Here, we develop an experimentally feasible approach to the evaluation of geometric measures of multiparticle entanglement. Our framework provides analytical results for particular classes of mixed states of N qubits, and computable lower bounds to global, partial, or genuine multiparticle entanglement of any general state. For global and partial entanglement, useful bounds are obtained with minimum effort, requiring local measurements in just three settings for any N. For genuine entanglement, a number of measurements scaling linearly with N are required. We demonstrate the power of our approach to estimate and quantify different types of multiparticle entanglement in a variety of N-qubit states useful for uantum information processing and recently engineered in laboratories with quantum optics and trapped ion setups

Workplace violence victimization in young workers: An analysis of the US National Crime Victimization Survey, 2008 to 2012

BACKGROUND: The aim of this study was to measure the frequency of workplace violence (WPV) victimization in 16 to 24-year olds in the United States and compare rates by occupation and demographics. METHODS: As an open cohort, participants 12 years or older in the National Crime Victimization Survey were interviewed at 6-month intervals over a 3-year period from 2008 to 2012. WPV victimization rates were calculated. Weighted, multilevel Poisson regression was used to compare WPV victimization rates by occupation and demographics. RESULTS: The rate of WPV victimization was 1.11 incidents per 1000 employed person-months (95% confidence interval: 0.95-1.27). The highest rates of WPV were in protective service occupations (5.24/1000 person-months), transportation (3.04/1000 person-months), and retail sales (2.29/1000 person-months). Compared with their respective counterparts, lower rates of WPV victimization were found among younger, black, and rural/suburban workers. CONCLUSIONS: Findings identify occupations and target populations in need of future research and evidence-based interventions to improve the working conditions for young workers