Spin–photon interface for a solid-state spin system via single trapped ion

An efficient spin–photon interface plays a significant role in building quantum network and distributed quantum computing with solid-state spin system, e.g., nitrogen-vacancy (NV) center in diamond. Solid-state spin system has the advantages of excellent portability and long coherence time, however, it suffers from a critical drawback of low efficiency of spontaneously emitted photons in the zero phonon line. This poses a severe challenge for the generation of an efficient interface between solid-state spin and photon. Here, we propose a method to establish a coherent interface between photon and solid-state spin system which is coupled to a trapped ion via a quantum transducer. Our method provides a new route to establish an efficient spin–photon interface allowing the generation of entanglement between distant spins.