Efficient controlled quantum secure direct communication based on GHZ-like states
In this paper, a three-party controlled quantum secure direct communication protocol based on GHZ-like state is proposed. In this scheme, the receiver can obtain the senders two secret bits under the permission of the controller. By using entanglement swapping, no qubits carrying secret messages are transmitted. Therefore, if the perfect quantum channel is used, the protocol is completely secure. The motivation behind utilizing GHZ-like state as a quantum channel is that if a qubit is lost in the GHZ-like state, the other two qubits are still entangled. The proposed protocol improves the efficiency of the previous ones.
efficiency controlled quantum secure direct communication ghz-like state entanglement swapping quantum cryptography