Polarization-stable long-distance interference of independent photons   for quantum communications
  Interference between fully-independent faint laser sources over two 8.5-km full polarization-controlled fiber links was performed, with stable visibility of 47.8%, an essential step towards practical implementation of quantum communication protocols. 
T. Ferreira da Silva, D. Vitoreti, G. B. Xavier, G. P. Tempor\~ao, and   J. P. von der Weid
quant-ph