# Experimental analysis of a four-qubit photon cluster state.

@article{Kiesel2005ExperimentalAO, title={Experimental analysis of a four-qubit photon cluster state.}, author={Nikolai Kiesel and Christian Schmid and Ulrich Weber and G{\'e}za T{\'o}th and Otfried G{\"u}hne and Rupert Ursin and Harald Weinfurter}, journal={Physical review letters}, year={2005}, volume={95 21}, pages={ 210502 } }

Linear-optics quantum logic operations enabled the observation of a four-photon cluster state. We prove genuine four-partite entanglement and study its persistency, demonstrating remarkable differences from the usual Greenberger-Horne-Zeilinger (GHZ) state. Efficient analysis tools are introduced in the experiment, which will be of great importance in further studies on multiparticle entangled states.

## 198 Citations

The entanglement of the four-photon cluster state

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Measurement based quantum computation draws its power from the remarkable entanglement properties of the cluster states. This contribution analyses the entanglement and its persistency of an…

Experimental measurement-based quantum computing beyond the cluster-state model

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Researchers propose a new type of multiphoton entangled state and demonstrate its working principles of measurement-based quantum computation in correlation space. With four- and six-qubit states,…

Optimal verification of entanglement in a photonic cluster state experiment

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We report on the quantification of entanglement by means of entanglement measures on a four- and a six-qubit cluster state realized by using photons entangled both in polarization and linear…

Simple experimental generation of a four-photon cluster state and distinguishing classes of genuine four-qubit entanglement using witness operators

- PhysicsQELS 2007
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We experimentally demonstrate a simple scheme for generating a four-photon cluster state. We show that the produced state has genuine four-qubit entanglement which is discriminated from a class…

Two-photon four-qubit cluster state generation based on a polarization-entangled photon pair.

- Physics, MedicineOptics express
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A two-photon four-qubit cluster state generator using linear optics and a single polarization-entangled photon-pair source based on spontaneous parametric down-conversion (SPDC) provides greater design flexibility compared to previous schemes that rely on hyperentanglement.

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We report on the experimental observation and analysis of four-photon entangled states. We analyze the particular entanglement properties of these states and introduce criteria, which enable the…

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- Physics
- 2007

We propose a scheme to generate a 4-qubit cluster of entangled coherent states in bimodal QED cavities. The scheme employs a single two-level atom that interacts dispersively with cavity modes…

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- Physics
- 2015

We propose an efficient method to construct an optical four-photon |χ〉 state analyzer via the cross-Kerr nonlinearity combined with linear optical elements. In this protocol, two four-qubit…

Experimental realization of one-way quantum computing with two-photon four-qubit cluster states.

- Physics, MedicinePhysical review letters
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This paper reports an experimental realization of one-way quantum computing on a two-photon four-qubit cluster state entangled both in polarization and spatial modes and implemented a highly efficient Grover's search algorithm and high-fidelity two-qubits quantum gates.

Experimental direct observation of mixed state entanglement.

- Physics, MedicinePhysical review letters
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It is demonstrated that the measured data, without need of further numerical processing, directly yield reliable estimates, despite experimental imperfections, on the direct estimation of concurrence for mixed quantum states.

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