Implementations of quantum and classical gates with linear optical   devices and photon number quantum non-demolition measurement for polarization   encoded qubits
  Aiming the construction of quantum computers and quantum communication systems based on optical devices, in this work we present possible implementations of quantum and classical CNOTs gates, as well an optical setup for generation and distribution of bipartite entangled states, using linear optical devices and photon number quantum non-demolition measurement. 
Joao Batista Rosa Silva and Rubens Viana Ramos