Quantum secure direct communication of continuous-time signals using Whittaker Nyquist Shannon theorem

In the present work, we provide a new quantum secure direct communication protocol and its experimental implementation. The proposed protocol can be used to transfer, in a secure way, continuous signals, like audio signal, from Alice to Bob. The security is guaranteed by the quantum nature of optical signals and the Whittaker-Nyquist-Shannon theorem. Furthermore, it can be easily implemented with common optical devices that are commercially available.