|This article needs additional citations for verification. (October 2015) (Learn how and when to remove this template message)|
In quantum information and quantum computing, a cluster state is a type of highly entangled state of multiple qubits. Cluster states are generated in lattices of qubits with Ising type interactions. A cluster C is a connected subset of a d-dimensional lattice, and a cluster state is a pure state of the qubits located on C. They are different from other types of entangled states such as GHZ states or W states in that it is more difficult to eliminate quantum entanglement (via projective measurements) in the case of cluster states. Another way of thinking of cluster states is as a particular instance of graph states, where the underlying graph is a connected subset of a d-dimensional lattice. Cluster states are especially useful in the context of the one-way quantum computer. For a comprehensible introduction to the topic see.
Formally, cluster states are states which obey the set eigenvalue equations:
where are the correlation operators
Cluster states have been realized experimentally. They have been obtained in photonic experiments using parametric downconversion  . They have been created also in optical lattices of cold atoms .
- H. J. Briegel; R. Raussendorf (2001). "Persistent Entanglement in arrays of Interacting Particles". Physical Review Letters. 86 (5): 910–3. arXiv: . Bibcode:2001PhRvL..86..910B. doi:10.1103/PhysRevLett.86.910. PMID 11177971.
- Briegel, Hans J. "Cluster States". In Greenberger, Daniel; Hentschel, Klaus & Weinert, Friedel. Compendium of Quantum Physics - Concepts, Experiments, History and Philosophy. Springer. pp. 96–105. ISBN 978-3-540-70622-9.
- P. Walther, K. J. Resch, T. Rudolph, E. Schenck, H. Weinfurter, V. Vedral, M. Aspelmeyer and A. Zeilinger (2005). "Experimental one-way quantum computing". Nature. 434 (7030): 169–76. arXiv: . Bibcode:2005Natur.434..169W. doi:10.1038/nature03347. PMID 15758991.
- N. Kiesel; C. Schmid; U. Weber; G. Tóth; O. Gühne; R. Ursin; H. Weinfurter (2005). "Experimental Analysis of a 4-Qubit Cluster State". Phys. Rev. Lett. 95: 210502. arXiv: . Bibcode:2005PhRvL..95u0502K. doi:10.1103/PhysRevLett.95.210502. PMID 16384122.
- O. Mandel; M. Greiner; A. Widera; T. Rom; T. W. Hänsch; I. Bloch (2003). "Controlled collisions for multi-particle entanglement of optically trapped atoms". Nature. 425: 937–940. arXiv: . Bibcode:2003Natur.425..937M. doi:10.1038/nature02008. PMID 14586463.
|This computer science article is a stub. You can help Wikipedia by expanding it.|