  Quantum fields on a stationary space-time in a rotating Killing reference
frame are considered. Finding solutions of wave equations in this frame is
reduced to a fiducial problem on a static background. The rotation results in a
gauge connection in a way similar to appearance of gauge fields in Kaluza-Klein
models. Such a Kaluza-Klein method in theory of rotating quantum fields enables
one to simplify computations and get a number of new results similar to those
established for static backgrounds. In particular, we find with its help
functional form of free energy at high temperatures. Applications of these
results to quantum fields near rotating black holes are briefly discussed.
