But how do the photons get together? The physicists’ theoretical model suggests that as a single photon moves through the cloud of rubidium, it hops from one atom to another, “like a bee flitting between flowers,” the press release explains. One photon can briefly bind to an atom, forming a hybrid photon-atom or polariton. If two of these polaritons meet in the cloud, they interact. When they reach the edge of the cloud, the atoms stay behind and the photons sail forward, still bound together. Add more photons and same phenomenon gives rise to triplets.