Polariton laser and polariton superfluidity in microcavities. A. Kavokin, G. Malpuech and F. P. Laussy in Phys. Lett. A 306:187 (2003).  What the paper says!?

This reviews the most important themes of polariton physics at the time, focusing on polariton condensation and polariton superfluidity.

The most challenging objective for this activity field is now without any doubt to clearly achieve po- lariton coherence in non-resonantly pumped micro-

cavities.

It «present[s] at a naive level the basic ideas of BEC and Kosterlitz–Thouless phase transition» and derive a polariton phase diagram based on textbook thermodynamic quantities for atomic systems.

It states that «stimulated scattering represents a dynamical aspect of Bose-condensation» (with a less restrictive criterion, Eq. (4)).

It makes the first, I think, mention of superfluidity for polaritons, although it takes a fairly simple and naive view of the problem.

Superfluidity means that two points on the surface are statistically con-

nected by a phase coherent path.