I wonder if near-UV like 380nm starts exciting the red receptor at 760nm like a resonant frequency or harmonic. Would also explain why something that's deeply

I wonder if near-UV like 380nm starts exciting the red receptor at 760nm like a resonant frequency or harmonic. Would also explain why something that's deeply red enough doesn't start looking purple, because the lower-energy photons can't get the higher energy receptors to trigger, unlike the other way around for deep blue. Which would make the color purple a distinctly quantum phenomenon.