Düsseldorf 2007 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 25: Quanteninformation (Verschränkung und Dekohärenz II)
Q 25.9: Talk
Tuesday, March 20, 2007, 16:15–16:30, 5L
Experimental Bell tests for quantum state discrimination — •Christian Schmid1,2, Nikolai Kiesel1,2, Wieslaw Laskowski3, Witlef Wieczorek1,2, Reinhold Pohlner1,2, and Harald Weinfurter1,2 — 1Max-Planck-Institute for Quantum Optics, Garching — 2Department for Physics, LMU Munich — 3Instytut Fizyki Teoretycznej i Astrofizyki, Uniwersytet Gdański, Poland
Bell inequalities provided the first experimental approach to reveal the discrepancy between quantum and classical correlations. For characterizing entangled states, recently, entanglement witnesses were developed. These turned out to be a mighty tool to distinguish multipartite states with a higher degree of separability from states with a lower one (e.g. [1]). However, quantum states composed of more than two qubits additionally offer a variety of types of entanglement. Here, we provide an approach how to construct Bell inequalities that are tailored to certain multipartite entangled states. They are constructed such that they witness non-classicality, non-separability and in addition distinguish between certain types of entanglement. We present two new Bell inequalities that are violated maximally by two important four-photon entangled states, D4(2) [2] and Ψ(4) [3], respectively. We demonstrate the resulting possibility to distinguish these states quantitatively from other relevant four-photon entangled states. Finally, we perform an experimental analysis of the state D4(2) based on this approach.
[1] M. Bourennane et al., Phys. Rev. Lett. 92, 087902 (2004),
[2] N. Kiesel et al., quant-ph/0606234 (2006),
[3] M. Eibl et al., Phys. Rev. Lett. 90, 200403 (2003)