On Demand Single Photon Detection

So we have this metamaterial structures in which we have a single nanoparticle inside them. And then because these have discrete energy levels, so when we excite an electron from ground state to the excited state,. So the electron recombines with the hole in the valence band and then emits a photon outBecause it's one photon absorbed will excite one electron up. When three emits, you get one photon out. That's the ideal scenario, right? The simplest way of doing is you take room light. It'll have billions of photons in what we see - but if you can put filters, like just some color insensitive filters... You can reduce the intensity to such a level that