Secure direct communication with a quantum one-time pad

TLDR

Quantum secure direct communication transmits secret messages without first establishing a shared key and can be useful in urgent situations. The authors propose a quantum secure direct communication protocol that uses single photons. The protocol employs batches of single photons prepared randomly in one of four states, serving as a one-time pad to encode messages in a single communication process. The protocol is unconditionally secure and feasible with current technology.

Abstract

Quantum secure direct communication is the direct communication of secret messages without first producing a shared secret key. It may be used in some urgent circumstances. Here we propose a quantum secure direct communication protocol using single photons. The protocol uses batches of single photons prepared randomly in one of four different states. These single photons serve as a one-time pad which is used directly to encode the secret messages in one communication process. We also show that it is unconditionally secure. The protocol is feasible with present-day technique.