Narrow Results

In this paper, we introduce a scheme of bidirectional quantum controlled teleportation for exchanging two single-qudit states via partially entangled GHZ-type states. The necessary measurements and operations are given in detail.

The protocols for jointly preparing three-particle state from a spatially separated multi-sender to one receiver are presented in this paper. The first scheme with two senders is proposed and shown to be a flexible deterministically. And then it is generalized to the multi-sender with improved success probability, by only adding some classical communications.

We show that any M ≥ 2 distant parties who independently share the complete classical knowledge of a secret qubit state can collectively prepare the state at another remote location. Two distinct schemes for such a task are proposed: one via a single (M + 1)-partite GHZ-type state and the other via M EPR-type pairs. Analytical expressions of the total success probability are derived explicitly for both the schemes. Of interest is the M-dependence of both the success probability and the receiver's action. We also construct simple quantum circuits for the two-qubit operators whose execution is necessary to accomplish the schemes.