We propose a quantum secure direct communication protocol using SU (2)-
invariant 2×N separable states, identified as separable equivalents of
two-qubit entangled Werner states in [Bharath & Ravishankar, Phys. Rev. A 89,
062110}]. These states can be experimentally realized as incoherent
superpositions of separable polarisation-OAM states.Comment: Accepted for oral presentation in International Conference on Quantum
Computing and Communications held at Bathinda, Punjab, Indi