Study On Controlled Quantum Secure Teleportation

In this paper, we first introduce recent research status and findings about quantum teleportation. We then describe several of previous important schemes about quantum teleportation. After a deep investigation of various existing quantum teleportation schemes, we propose two improved schemes for controlled teleportation. The first scheme is entitled as controlled teleportation with the control of two groups of agents. In this scheme, we present a way for implementing controlled teleportation of an arbitrary unknown pure state of a qutrit with the control of two groups of agents. The sender can successfully and safely teleport the qutrit state to a distant receiver with the help of all agents. However, if one agent in each group does not cooperate, the receiver cannot gain any information about the qutrit state to be teleported. In addition, we have discussed the security of this scheme against eavesdropping attack. The second scheme is named as a phase-based controlled teleportation via EPR pairs. In this scheme, the original information to be teleported is encrypted via the phase encoding. Different from previous proposals for multi-party controlled quantum teleportation using GHZ states, this scheme only needs EPR pairs and thus is easier to implement in experiment.