Regensburg 2004 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 50: Entanglement and Decoherence
DY 50.1: Hauptvortrag
Freitag, 12. März 2004, 10:15–10:45, H2
How can entanglement between three or more qubits be measured? — •Jens Siewert1 and Andreas Osterloh2 — 1Institut fuer Theoretische Physik, Universitaet Regensburg, D-93040 Regensburg, Germany — 2Dipartimento di Metodologie Fisiche e Chimiche per l’Ingegneria, Universita di Catania, I-95125 Catania, Italy
Entanglement is, apart from its importance as a fundamental concept in quantum mechanics, a key resource for quantum information processing. While it is easy to say whether or not a given pure state of N qubits is factorizable, it is a much more delicate question to quantify how much it is entangled, even more so for mixed states. A well-known entanglement measure for two qubits is the so-called concurrence (or 2-tangle) [1,2] which is applicable for both pure and mixed states. While there exists an analogous measure for pure states of three qubits [2], no N-tangle is known for N=3 mixed states or any state with N>3. In this contribution, the question is discussed what the “underlying principles” for the N-tangle are, and how they can be generalized to N>3.
[1] S. Hill and W.K. Wootters, Phys. Rev. Lett. 80, 2245 (1998).
[2] V. Coffman, J. Kundu, and W.K. Wootters, Phys. Rev. A 61, 052306 (2000).