The result of that process? As the photons exited the cloud, they were clumped together. That's a result of the nearby atoms; when one atom is excited, nearby atoms cannot be excited to the same degree, in an effect called a Rydberg blockade. So when a photon comes in, it excites nearby atoms, but when the next photon enters the cloud, it would excite nearby atoms to the same degree--which it can't do. So the first photon has to move out of the way. That's an interaction between photons, sort of, but with atoms as a mediator. What it means is that the two photons end up pushing and pulling each other through the cloud of atoms, and when they exit the cloud, they're clumped like a molecule, thanks to that continued interaction.