Efficient Quantum Secure Direct Communication Using the Orbital Angular Momentum of Single Photons

Abstract

Quantum secure direct communication (QSDC) is to transmit information directly through quantum channels without generating secret keys. The efficiencies of QSDC rely on the capacity of qubits. Exploiting orbital angular momentum of single photons, we proposed a high-capacity one-time pad QSDC protocol. The information is encoded on the Hermite-Gauss mode and transmitted directly on the Laguerre-Gauss mode of the photon pluses. The proposed system provides a high coding space, and the proposed protocol is robust against collective-dephasing channel noise.

The Evolution of Quantum Secure Direct Communication: On the Road to the Qinternet

“…For a given azimuthal index 𝑙, the orbital angular momentum has the discrete value of 𝐿 = 𝑙ℏ, indicating that the beam carries 𝑙ℏ amount of orbital angular momentum per photon. It has been demonstrated that orbital angular momentum states can be used for conveying information at a capacity beyond one bit per photon both for QSDC [305], [328] and DQKD [329]. Additionally, a high-dimensional system 'qudit' (a unit of information in a 𝑁 dimension space) typically has a superior security level in quantum cryptography protocols [330], [331].…”

“…While still relying on the basic principles of the earliest QSDC schemes, we can choose different physical entities to implement QSDC [65], [66], [76], [81], [85], [305], [328], [341], [371]- [378]. There are three foundamental features of a peer-to-peer QSDC protocol [49]:…”