Berlin 2001 – scientific programme
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Q: Quantenoptik
Q 9: Poster: Quantum Information
Q 9.6: Poster
Tuesday, April 3, 2001, 12:30–15:00, AT2
Multiparticle entanglement purification — •Aldo Delgado1, Gernot Alber1, and Igor Jex2 — 1Abteilung fuer Quantenphysik, Universitaet Ulm — 2Department of Physics, FNSPE Czech Technical University Prague
Entanglement plays an important role in quantum information processing. It allows processes such as quantum teleportation, quantum cryptography and quantum state and key sharing. Unfortunately, entanglement is a very fragile resource. Any coupling with the environment leads to dissipative effects which turn entangled pure states into mixed states. However, the environment does not always destroy the entanglement completely. In this case it is possible to use entanglement purification protocols which produce maximally entangled pure states from mixed states. In this contribution we present an entanglement purification protocol based on a non-linear quantum operation and the Fourier transformation. This protocol is able to purify Werner states up to the separability limit in arbitrary finite dimensional Hilbert spaces and achieves a higher efficiency than previously known protocols [1]. Motivated by recent applications of multiparticle entanglement to quantum state and key sharing we extend the protocol to the direct purification of Aharonov states and GHZ states. In the latter case the protocol has a better range of convergence than the protocol proposed in Ref. [2].
[1] M. Horodecki and P. Horodecki, Phys. Rev. A 59, 4206 (1999)
[2] M. Murao, M. B. Plenio, S. Popescu, V. Vedral and P. L. Knight Phys. Rev. A 57, R4075 (1998)