Epr Entanglement-based Quantum Key Distribution And Non-key Quantum Direct Communication Program

Quantum entanglement was first recognized as a feature of quantum mechanics in the famous paper of Einstein, Podolsky and Rosen . Recently it has been realized that quantum entanglement is a key ingredient in quantum computation, quantum communication and quantum cryptography.For communication, we have the desire and need to transmit secret messages from one person to another. We have the cryptography - an art to transmit information. But, with the development of quantum computation, the most important classic cryptographic scheme named public-key crypto-system will be aggressed easily. The principle of the quantum mechanics can only help to make the key distribution secure. In section II, we present a theoretical quantum key distribution scheme using EPR pairs. This scheme does not require that Alice and Bob choose between alternative measurements, therefore improving the generating rate of key bits. At the same time, in this scheme detecting Eve requires the comparison of fewer bits.Different from key distribution whose object is to establish a common random key between two parties, a secure direct communication is to communicate important messages directly without first establishing a random key to encrypt them. Thus secure direct communication is more demanding on the security. As classical message can be copied fully, it is impossible to transmit secret messages directly through classical channels. But when quantum mechanics enters into the communication, the story will change. In section III, we present a theoretical quantum communication scheme using EPR pairs and quantum teleportation. This scheme does not require teleport the qubit which carry the secret message between Alice and Bob.