  An extended Josephson junction intrinsically couples the superconducting
current to the microwave cavity in the insulating barrier. We demonstrate that
this coupling produces sidebands in the microwave cavity resonances of the
junction. By measuring the switching current distribution, we show that
microwave radiation at sidebands brings the Josephson phase out of equilibrium.
In particular, the effective phase temperature is reduced or enhanced through
anti-Stokes and Stokes scattering, respectively. Phase cooling and heating both
increase with microwave power.
