Berlin 2001 – scientific programme
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Q: Quantenoptik
Q 15: Quantum Information IV
Q 15.3: Talk
Tuesday, April 3, 2001, 18:00–18:15, H 3010
New entangled multiphoton state — •Sascha Gaertner1, Manfred Eibl2, Christian Kurtsiefer1, Harald Weinfurter1,2, and Marek Zukowski3 — 1Ludwig-Maximilians-Universität München (LMU), LMU München, Sektion Physik, Schellingstrasse 4/III, 80799 München — 2Max-Planck-Institut für Quantenoptik (MPQ), MPQ, Hans-Kopfermann-Str.1, 85748 Garching — 3Instytut Fizyki Teoretyczney i Astrofizyki, Uniwersytet Gdanski, PL-80-952 Gdansk, Poland
Multiphoton entanglement is the basis of new quantum communication schemes like quantum cloning, quantum secret sharing and teleportation of entanglement. Moreover it is the cornerstone of new studies of local realistic theories and the study of novel features of multiparticle entanglement and decoherence.
Among the multiphoton states until today only the three and four photon GHZ-states [1,2,3] are experimentally realized. We describe the generation of a new entangled multiphoton state with pulsed type II parametric downconversion. In cw-downconversion one usually produces pairs of polarization-entangled photons. For pulsed downconversion sources there is a non-negligible probability to get two pairs emitted simultaneously. Due to bosonic interference this new state is a superposition of a 4 photon GHZ-state and a product of two Bell-states. Whereas a 4-photon GHZ-state exhibits pure 4 particle entanglement this new state has in addition entanglement between photons in the same arm. Although this state is only partially entangled it strongly violates a generalized 4-particle Bell inequality.
[1] D.Bouwmeester, J.W. Pan, M. Daniell, H. Weinfurter, A. Zeilinger, PRL 82, 1345 (1999) [2] A. Zeilinger, M. Horne, H. Weinfurter, M. Zukowski, PRL 78, 3031 (1997) [3] private communication J.W. Pan, M. Daniell, G. Weihs, A. Zeilinger