A new theoretical quantum key distribution scheme based on entanglement swapping is proposed, where four-qubit symmetric W state functions as quantum channel. It is shown that two legitimate users can secretly share a series of key bits by using Bell-state measurements and classical communication.
In order to enhance the efficiency of quantum key distribution( QKD),a protocol based on entanglement swapping is proposed. Without classical information exchange or unitary operations,the two communication parts can securely share a session key by entanglement swapping and Bell measurement. Almost all qubits,except a few which are used to check the security of quantum channel,can produce the private key,and two pairs of entangled particles can generate two bits private key. The protocol is proved to secure using Stinespring Dilation Theorem and the efficiency analysis is presented.
A new theoretical scheme for quantum secure direct communication is proposed, where four-qubit symmetric W state functions as quantum channel. It is shown that two legitimate users can directly transmit the secret messages by using Bell-basis measurements and classical communication. The scheme is completely secure if the quantum channel is perfect. Even if the quantum channel is unsecured, it is still possible for two users to perform their secure communication. One bit secret message can be transmitted by sending a bit classical information.
In order to distribute a secret key between two designated users, a mutually authenticated quantum key distribution (QKD) protocol based on entanglement swapping is proposed. Without classical information exchange, the two communication parts can securely share a session key in this protocol. Almost all qubits, except a few which are used to check the security of quantum channel, can produce the private key, and two pairs of entangled particles can generate two bits private key. The protocol is proved to secure using Stinespring dilation theorem, and the efficiency analysis is presented.