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arXiv · 1504.05934

Closing the detection loophole in tripartite Bell tests using the W state

Karoly F. Pal·Tamas Vertesi
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Abstract

We study the problem of closing the detection loophole in three-qubit Bell tests, the experimentally most relevant case beyond the usual bipartite scenario, and show that the minimal detection efficiencies required can be considerably lowered compared to the two-qubit case. The lowest reported detection efficiency thresholds for two and three qubits so far are $\sim66.7\%$ and $60\%$, respectively. Using the three-qubit W state and a 3-setting Bell inequality, we beat these thresholds and with an 8-setting Bell inequality we reach $50.13\%$. We also investigate generic three-qubit states which allow us to attain a detection efficiency of $50\%$ in a 4-setting Bell test. We conjecture that the limit of $50\%$ is unbeatable using three-qubit states and any number of measurements.

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Karoly F. Pal, Tamas Vertesi. 2015-04-22. Closing the detection loophole in tripartite Bell tests using the W state. https://doi.org/10.1103/physreva.92.022103

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