An optical-microwave-quantum transducer can include a tapered optical fiber configured to transmit and receive optical signals. The optical-microwave-quantum transducer can also include a cantilever that can include an optical cavity that includes a nanophotonic crystal. The optical cavity can be configured to provide mechanical excitation in response to electromagnetic excitation induced by photons emitted from the tapered optical fiber. The cantilever can also include a mechanical coupler that is configured to induce electrical modulation onto a superconducting cavity in response to the mechanical excitation. The mechanical coupler can also be configured to provide mechanical excitation in response to electromagnetic excitation induced by photons from the superconducting cavity. The optical cavity can further be configured to provide electromagnetic excitation that induces optical modulation on the tapered optical fiber in response to the mechanical excitation.