Quantum Key Distribution Using Spin Wave–Optical Interactions
Pradeep K Kumar, Anil Prabhakar · IEEE Journal of Quantum Electronics · 2010
We propose the use of spin wave–optical interactions to implement the BB84 and B92 quantum key distribution (QKD) protocols. Spin waves couple the transverse magnetic (TM) and transverse electric (TE) optical modes of a waveguide. We derive the interaction Hamiltonian to describe the coupling, and solve the resulting equations to determine the time evolution of quantized TM and TE modes. With a judicious choice of coupling coefficient, a set of four nonorthogonal states-formally equivalent to the set of polarization states of a single photon-can be generated. These states form a conjugate basis suitable as a QKD basis set. The proposed scheme can mitigate any medium-induced polarization fluctuations. The spin wave–optical interactions can be used to implement the BB84 protocol using frequency-coded coherent optical states.