[Alohascope (OP)]

Photonic molocules.  http://phys.org/news/2013-09-scientists-never-before-seen.html.

[Colin2B]

You might look up Prof Lena Hau. She did work slowing down light in Bose-Einstein condensate and I think she found some photon interactions.

[puppypower]

When photons interacts with the charges on atoms, the charges will attempt to align their EM wave with the EM wave of the photon. But because the charge is attached to an atom, there is a time delay in the EM field of the charge, due to the constraints of inertia. The charge is heavier and and will follow the EM wave of the photon, but will lag behind. The result is the two waves can add to create a composite wave that reflects the photon-charge system. This is represented below.

Conceptually, there is no reason this can't be scaled up, where two photons are interacting with two separate but close charges, to get two composite waves, which themselves add to form a larger composite wave. This allows the two waves of two photons to act like they are part of one wave; mediated by matter. The particles remain distinct, so when the composite comes undone; exit, the particles reestablish their normal distinct waves.

[Alohascope (OP)]

When photons interacts with the charges on atoms, the charges will attempt to align their EM wave with the EM wave of the photon. But because the charge is attached to an atom, there is a time delay in the EM field of the charge, due to the constraints of inertia. The charge is heavier and and will follow the EM wave of the photon, but will lag behind. The result is the two waves can add to create a composite wave that reflects the photon-charge system. This is represented below.

Conceptually, there is no reason this can't be scaled up, where two photons are interacting with two separate but close charges, to get two composite waves, which themselves add to form a larger composite wave. This allows the two waves of two photons to act like they are part of one wave; mediated by matter. The particles remain distinct, so when the composite comes undone; exit, the particles reestablish their normal distinct waves.

Wow .. someone who sounds like they actually know something!  Not that the others here don't sound like they know something, they do, I hope I don't get myself into trouble here for a compliment.