Quantum networks based on spins and photons are strong candidates for future quantum computation and communication devices. In such networks, the spins are used to store and manipulate quantum information, while the photons are used to link separate spins. This architecture is highly advantageous as it combines the excellent quantum properties of spins, including long coherence lifetimes and high-fidelity quantum operations, with the flexibility and resilience of photons, which can be routed through rapidly reconfigurable switching networks and are impervious to many environmental disturbances. A key benefit of this combination is that losses, which are the most important hindrance to all-photonic systems, can be overcome by using repeat-until-success strategies in the quantum connections between the spins. These architectures require a quantum system with spin-dependent transitions, such as an atom, an ion, or an impurity in a crystal, to be integrated in a photonic enhancement structure which acts as a spin-photon interface (SPI), wherein the quantum information can be transferred between the static spin and the travelling photon.

We have identified vanadium in silicon carbide (SiC) as a highly promising candidate for the implementation of such an architecture. This defect has a strong optical transition in the optical telecom range, allowing to leverage the high-quality routing and switching devices available in that domain. The extremely high quality of SiC materials that has been reached by the power electronics industry makes this material an ideal host for large-scale quantum systems, and provides a clear path towards industrial exploitation.

We have demonstrated that vanadium in SiC has a long spin lifetime, and its rich hyperfine structure is ideally suited for the encoding of qudits.