Optimal transfer of an unknown state via a bipartite quantum operation
1 Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences Beijing 100190, China
2 School of Physics and Electronic Science, Changsha University of Science and Technology Changsha 410114, China
Received: 31 January 2013
Accepted: 22 May 2013
A fundamental task in quantum information science is to transfer an unknown state from particle A to particle B (often in remote space locations) by using a bipartite quantum operation . We suggest the power of for quantum state transfer (QST) to be the maximal average probability of QST over the initial states of particle B and the identifications of the state vectors between A and B. We find the QST power of a bipartite quantum operations satisfies four desired properties between two d-dimensional Hilbert spaces. When A and B are qubits, the analytical expressions of the QST power is given. The numerical result on a QST scheme via a quantum wire shows the necessity to optimize the average fidelity. In particular, we obtain the exact results of the QST power for a general two-qubit unitary transformation, and we find a necessary and sufficient condition for the two-qubit unitary gates with perfect QST.
PACS: 03.67.Ac – Quantum algorithms, protocols, and simulations / 03.65.-w – Quantum mechanics / 03.67.Hk – Quantum communication
© EPLA, 2013