Quantum spread spectrum multiple access
  We describe a quantum multiple access scheme that can take separate single photon channels and combine them in the same path. We propose an add-drop multiplexer that can insert or extract a single photon into an optical fibre carrying the qubits of all the other users. The system follows the principle of code division multiple access, a spread spectrum technique widely used in cellular networks. 
Juan Carlos Garcia-Escartin and Pedro Chamorro-Posada
quant-ph