  We propose networking superconducting quantum circuits by transducing their
excitations (typically 4-8 GHz) to 100-500 MHz photons for transmission via
cryogenic coaxial cables. Counter-intuitively, this frequency downconversion
reduces noise and transmission losses. We introduce a multi-octave
asymmetrically threaded SQUID circuit (MOATS) capable of the required
efficient, high-rate transduction. For a 100-meter cable with $Q_i = 10^5$ at
10 mK, our approach achieves single-photon fidelities of 0.962 at 200 MHz
versus 0.772 at 8 GHz, and triples the lower bound on quantum channel capacity.
This method enables kilometer-scale quantum links while maintaining high
fidelities, combining improved performance with the practical advantages of
flexible, compact coaxial cables.
