Quantum network and quantum router based on superconducting circuits

The quantum computing devices based on superconducting circuits have already been developed into the stage called Noisy Intermediate-Scale Quantum (NISQ), the relevant technologies of fabrication, control and measurement is relatively mature. However, the scaling of superconducting circuits is still hard, thus distributed quantum computation become one of the ways of further enhancing the computing power of the whole system. Then we need to build a quantum network and connect quantum computing devices together. The elementary quantum network is constituded by end notes, quantum repeaters and communication channels. When the scale of the network becomes large, the function of distributing quantum information to different end notes becomes important, so quantum router occurs. Contrary to classical router in classical network, quantum routers are able to route quantum information coherently and form a entanglement state between output channels. There are quantum router prototypes based on three types of physical systems:cavity QED systems、pure linear-optical systems and superconducting circuits in experiment. Although quantum router based on superconducting circuits route microwave photons rather than optical photons with 1.5 microns wavelength, the routing process of quantum router based on superconducting circuits is deterministic rather than probabilistic and the routing efficiency is higher in contrast to that based on cavity QED systems and pure linear-optical systems, which provides application scenarios in at least a small scale quantum network.