Magnon-Photon interactions for Quantum Key Distribution

We propose an implementation of quantum key distribution (QKD) protocol using magnon-photon interactions in dielectric waveguides. Starting from the Hamiltonian of spin wave-optical interactions in asymmetric dielectric waveguide, we derive the single-photon transformations that allow us to define two non-orthogonal basis sets, which are isomorphic to polarization basis of single-photon. Implementation of the BB84 and B92 protocols is then straight forward. The principal advantage of our scheme is the higher quantum bit error rate (QBER) (37.5%) compared to polarization-coded scheme (25%) for simple intercept/resend attack. This considerably relaxes the specifications of optical components. Finally, we consider the effect of low conversion efficiency on QBER.