Cooling many particles at once
  We propose a mechanism for the collective cooling of a large number N of trapped particles to very low temperatures by applying red-detuned laser fields and coupling them to the quantized field inside an optical resonator. The dynamics is described by what appears to be rate equations, but where some of the major quantities are coherences and not populations. The cooperative behavior of the system provides cooling rates of the same order of magnitude as the cavity decay rate kappa. This constitutes a significant speed-up compared to other cooling mechanisms since kappa can, in principle, be as large as square root of N times the single-particle cavity or laser coupling constant. 
Almut Beige, Peter L. Knight, and Giuseppe Vitiello