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Q: Fachverband Quantenoptik und Photonik
Q 18: Quanteninformation (Verschränkung und Dekohärenz I)
Q 18.1: Group Report
Tuesday, March 20, 2007, 10:30–11:00, 5L
An observable entanglement measure — •Florian Mintert1, Leandro Aolita2,3, Rafal Demkowicz Dobrzanski4, Stephen Walborn2, Paulo Souto Ribeiro2, Luiz Davidovich2, Marek Kus4, and Andreas Buchleitner3 — 1Department of Physics, Harvard University — 2Universidade Federal do Rio de Janeiro — 3Max Planck Institut fuer Physik Komplexer Systeme, Dresden — 4Centrum Fizyki Teoretycznej Polskiej Akademii Nauk, Warszawa
Although entanglement constitutes one of the most remarkable differences between classical and quantum mechanics, and it does have directly observable consequences, it is not an observable like for example momentum or energy. Unlike a regular observable that has an associated hermitean operator, an entanglement measure is rather a non-linear functional of a large set of such observables. Therefore, one typically needs to perform many different measurements, in order to determine the degree of entanglement of a given quantum state. We show, how the entanglement measure concurrence is given in terms of collective observables of two identically prepared quantum states. This allows for a direct experimental estimate of the concurrence of arbitrary finite dimensional quantum states as it is demonstrated in a laboratory experiments with pure twin photon states.