Düsseldorf 2007 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 18: Quanteninformation (Verschränkung und Dekohärenz I)

Q 18.1: Gruppenbericht

Dienstag, 20. März 2007, 10:30–11:00, 5L

An observable entanglement measure — •Florian Mintert¹, Leandro Aolita^2,3, 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.