  A circulator is one of the crucial devices in quantum networks and
simulations. We propose a four-port circulator that regulate the flow of single
photons at muti-frequency points by studying the coherent transmission of a
single photon in a coupled system of two resonators and two waveguides. When
both resonators are static or rotate at the same angular velocity,
single-photon transport demonstrates reciprocity; however, when the angular
velocities differ, four distinct frequency points emerge where photon
circulation can occur. In particular, when the angular velocities of the two
resonators are equal and opposite, there are two different frequency points
where photon circulation can be achieved, and there is a frequency point where
a single photon input from any waveguide can be completely routed to the other
waveguide. Interestingly, by rotating the two resonators, the single-photon
circulation suppressed by the internal defect-induced backscattering can be
restored.
