Splitting unknown two-qubit pure or mixed state via one-dimensional six-qubit cluster state

We first propose a tripartite quantum information splitting (QIS) scheme for splitting an unknown two-qubit pure state by using a one-dimensional six-qubit cluster state channel. In this scheme, three Bell state measurements (BSMs) and a two-qubit unitary operation (TQUO) are indispensable. Second we put forward an improved QIS scheme for splitting a two-qubit pure state based on a newly proposed distribution of the channel qubits. In the second QIS scheme, only two BSMs, two single-qubit measurements and a TQUO are necessary. Compared with our first scheme, the operation difficulty is reduced in our second scheme. At last, we generalize the two QIS schemes for splitting an arbitrary two-qubit mixed state. Our QIS schemes can be realized in the linear optical systems. (C) 2012 Elsevier B.V. All rights reserved.