High-NOON States with High Flux of Photons Using Coherent Beam Stimulated Noncollinear Parametric Down Conversion

Figure 4

The fidelity plots for 4-NOON states. (a) The fidelity of interferometer state’s N photon component with NOON state with N = 4 for weak fields. The horizontal axis is the phase of the coherent field. The phase of PDC is chosen to be zero. Here, the gain parameter of the PDC is and the amplitude ratio is optimized at for the maximum fidelity of . The maximum fidelity is reached at phases of 0 and π. This is much better than the case (with down-converted photons only) with a fidelity of 75% and the case (coherent fields only) with a fidelity of 50%. (b) The fidelity profile in the limit of high gain with (this gain has been reported in [30]). The black, red, and blue curves are with fidelities of 92%, 90%, and 81%, respectively. It is clear from the plots that we have much more flexibility in pair amplitude ratio. By choosing a larger amplitude ratio, we can reach a total flux of coherent state pair photons having approximately 3 orders of magnitude higher than PDC pair photons.

(a)

(b)