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Phys. Rev. A 76, 030305(R) (2007) [4 pages]

Toolbox for entanglement detection and fidelity estimation

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Otfried Gühne1, Chao-Yang Lu2, Wei-Bo Gao2, and Jian-Wei Pan2,3
1Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
2Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
3Physikalisches Institut, Universität Heidelberg, Philosophenweg 12, D-69120 Heidelberg, Germany

Received 1 July 2007; published 18 September 2007

The determination of the state fidelity and the detection of entanglement are fundamental problems in quantum information experiments. We investigate how these goals can be achieved with a minimal effort. We show that the fidelity of Greenberger-Horne-Zeilinger and W states can be determined with an effort increasing only linearly with the number of qubits. We also present simple and robust methods for other states, such as cluster states and states in decoherence-free subspaces.

© 2007 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevA.76.030305
DOI:
10.1103/PhysRevA.76.030305
PACS:
03.67.Mn, 03.65.Ud
 
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