Quantum secure direct communication by Einstein-Podolsky-Rosen pairs and entanglement swapping

TL;DR

This paper proposes a quantum secure direct communication protocol using EPR pairs and entanglement swapping, enabling direct message transmission without transmitting message-carrying qubits over the public channel.

Contribution

It introduces a novel quantum communication scheme that leverages entanglement swapping and EPR pairs for secure direct message transfer, enhancing security and efficiency.

Findings

Secure direct communication with three EPR pairs achieved

No message qubits transmitted over the public channel

Protocol is secure with perfect quantum channels

Abstract

We present a quantum secure direct communication scheme achieved by swapping quantum entanglement. In this scheme a set of ordered Einstein-Podolsky-Rosen (EPR) pairs is used as a quantum information channel for sending secret messages directly. After insuring the safety of the quantum channel, the sender Alice encodes the secret messages directly by applying a series local operations on her particles sequence according to their stipulation. Using three EPR pairs, three bits of secret classical information can be faithfully transmitted from Alice to remote Bob without revealing any information to a potential eavesdropper. By both Alice and Bob's GHZ state measurement results, Bob is able to read out the encoded secret messages directly. The protocol is completely secure if perfect quantum channel is used, because there is not a transmission of the qubits carrying the secret message between Alice and Bob in the public channel.