Photonic multipartite entanglement conversion using nonlocal operations

We propose a simple setup for the conversion of multipartite entangled states in a quantum network with restricted access. The scheme uses nonlocal operations to enable the preparation of states that are inequivalent under local operations and classical communication, but most importantly does not require full access to the states. It is based on a flexible linear optical conversion gate that uses photons, which are ideally suited for distributed quantum computation and quantum communication in extended networks. In order to show the basic working principles of the gate, we focus on converting a four-qubit entangled cluster state to other locally inequivalent four-qubit states, such as the GHZ and symmetric Dicke state. We also show how the gate can be incorporated into extended graph state networks, and can be used to generate variable entanglement and quantum correlations without entanglement but nonvanishing quantum discord.Comment: 10 pages, 6 figures, correction of reference list, add Journal ref. and DO

Faithful qubit distribution assisted by one additional qubit against collective noise

We propose a distribution scheme of polarization states of a single photon over collective-noise channel. By adding one extra photon with a fixed polarization, we can protect the state against collective noise via a parity-check measurement and post-selection. While the scheme succeeds only probabilistically, it is simpler and more flexible than the schemes utilizing decoherence-free subspace. An application to BB84 protocol through collective noise channel, which is robust to the Trojan horse attack, is also given.Comment: 4 pages, 3 figures; published version in Phys. Rev. Let

EVALUATION OF FITNESS CENTER SERVICE QUALITY THROUGH IMPORTANCE-PERFORMANCE ANALYSIS

Various methods are used to evaluate service quality. This study aimed to evaluate the quality of service in a fitness center through the importance-performance analysis (IPA) by focusing on the fitness center customers. The data were obtained from a commercial fitness center. The Service Quality Scale for Fitness Centers (SQS-FC) for fitness centers developed by Yildiz (2011) was used as a data collection tool. The study result showed that IPA is an effective method to evaluate the service quality of fitness centers. Evaluations were made regarding missing and weak service attributes through IPA.  Article visualizations

An elementary optical gate for expanding entanglement web

We introduce an elementary optical gate for expanding polarization entangled W states, in which every pair of photons are entangled alike. The gate is composed of a pair of 50:50 beamsplitters and ancillary photons in the two-photon Fock state. By seeding one of the photons in an $n$-photon W state into this gate, we obtain an $(n+2)$-photon W state after post-selection. This gate gives a better efficiency and a simpler implementation than previous proposals for $\rm W$-state preparation.Comment: 5 pages, 2 figures. To appear in Phys. Rev.

Demonstration of local expansion toward large-scale entangled webs

We demonstrate an optical gate that increases the size of polarization-based W states by accessing only one of the qubits. Using this gate, we have generated three-photon and four-photon W states with fidelities $0.836\pm 0.042$ and $0.784\pm 0.028$, respectively. We also confirmed existence of pairwise entanglement in every pair of the qubits including the one that was left untouched by the gate. The gate is applicable to any size of W states and hence is a universal tool for expanding entanglement.Comment: 5 pages, 4 figure