What if we could use electron energy levels in a molecule to mediate a light-based gate? (Sorry in advance for imprecise terminology...) Lets say we have a mo

What if we could use electron energy levels in a molecule to mediate a light-based gate? (Sorry in advance for imprecise terminology...) Lets say we have a molecule with two energetic orbital states. An electron in the Ground state (G) can be lifted to Orbital 1 (O1) by photon with wavelength A, and can be lifted from there to Orbital 2 (O2) by a different photon of wavelength B. Photon B alone is too energetic to lift from G->O1, and not energetic enough to lift directly from G->O2, where photon A is exactly enough to lift from G->O1. So the gate would be set by photon A raising the orbital from G->O1, and the gate is read by sending photon B which is only absorbed if A has already been absorbed. Compose multiple such gates by designing a pair (or more) of molecules where the wavelengths of A & B are swapped, so that the first molecule's B photon is the second molecule's A photon, etc. Maybe recover energy from excited orbitals by passing a laser of each wavelength through all the molecules at the end of each 'cycle', inducing the molecule to emit any absorbed photons in a useful direction to be recycled. Thoughts?