Phys. Rev. A 64, 042315 (2001) [13 pages]Universal state inversion and concurrence in arbitrary dimensions
Pranaw Rungta1, V. Bužek2 *, Carlton M. Caves1, M. Hillery3, and G. J. Milburn4 Received 13 February 2001; published 18 September 2001 Wootters [Phys. Rev. Lett. 80, 2245 (1998)] has given an explicit formula for the entanglement of formation of two qubits in terms of what he calls the concurrence of the joint density operator. Wootters’s concurrence is defined with the help of the superoperator that flips the spin of a qubit. We generalize the spin-flip superoperator to a “universal inverter,” which acts on quantum systems of arbitrary dimension, and we introduce the corresponding generalized concurrence for joint pure states of D1×D2 bipartite quantum systems. We call this generalized concurrence the I concurrence to emphasize its relation to the universal inverter. The universal inverter, which is a positive, but not completely positive superoperator, is closely related to the completely positive universal-not superoperator, the quantum analogue of a classical not gate. We present a physical realization of the universal-not superoperator. ©2001 The American Physical Society
URL: http://link.aps.org/doi/10.1103/PhysRevA.64.042315 * Permanent address: Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 842 28 Bratislava, Slovakia, and Faculty of Informatics, Masaryk University, Botanická 68a, 602 00 Brno, Czech Republic. [ Abstract | Previous article | Next article | Issue 4 ] |
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