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Efficient detection of useful long-range entanglement in imperfect cluster states

Nutz, Thomas; Milne, Antony; Shadbolt, Pete and Rudolph, Terry. 2017. Efficient detection of useful long-range entanglement in imperfect cluster states. APL Photonics, 2, [Article]

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Abstract or Description

Photonic cluster states are a crucial resource for optical quantum computing. Recently a quantum dot single photon source has been demonstrated to produce strings of photons in a linear cluster state, but high photon loss rates make it impossible to characterize the entanglement generated by conventional methods. We present a benchmarking method for such sources that can be used to demonstrate useful long-range entanglement with currently available collection/detection efficiencies below 1%. Measurement of the polarization state of single photons in different bases can provide an estimate for the three-qubit correlation function hZXZi. This value constrains correlations spanning more than three qubits, which in turn provide a lower bound for the localizable
entanglement between any two qubits in the large state produced by the source. Finite localizable entanglement can be established by demonstrating hZXZi > 2 3 . This result enables photonic experiments demonstrating
computationally useful entanglement with currently available technology.

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27 May 2017Published Online
27 May 2017Accepted

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Date Deposited:

20 Nov 2018 18:35

Last Modified:

21 Nov 2018 17:40


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