(3)
Abstract:
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 de-ned with the help of the superoperator that ips the spin of a qubit. We generalize the spin- ip 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 D 1 D 2 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. I.
Citations
| 7 | Introduction to Quantum Computation and Information, edited by – Lo, Popescu, et al. - 1998 |
| 3 | address: Institute of Physics, Slovak Academy of Sciences, Dubravska cesta 9 – Permanent |
| 3 | Quantum Optics: A Collection of Papers Dedicated to the Memory of Dan Walls, edited by – Rungta, Munro, et al. - 2000 |
| 3 | unpublished, e-print quant-ph/0001053 – Yu |
