Engineering multiphoton entangled states by quantum interference
B. Liu, Z. Y. Ou · Physical Review A · 2006
By combining a coherent state with fields from a number of parametric down-conversion processes, we are able to generate arbitrary $N$-photon entangled states, including the maximally entangled photon-number state or the so-called NOON state $(\ensuremath{\mid}N,0⟩+\ensuremath{\mid}0,N⟩)$. This is achieved through destructive quantum interference for the cancellation of the unwanted states.