A quantum secure direct communication protocol using entangled beam pairs

Abstract

We propose a feasible high-dimensional two-step quantum secure direct communication scheme by using the Einstein-Podolsky-Rosen entangled beam pair. Accoding to the quality of the two superposition forms of the EPR entangled state (two-mode squeezed vacuum state), we select the mutually unbiased bases for quantum measurement. With the unitary operation, we can subtly encode the confidential information in the quantum state. We also conducted a more detailed analysis of the security of this protocol.