Quantum teleportation of a photon via absorption and emission for quantum repeater nodes

Absorption and emission, fundamental interactions between light and matter, enable the regeneration of a quantum state of light via matter through concatenated quantum state transfer based on the principle of quantum teleportation. This transfer is enabled by electron spin‒orbit entanglement and electron‒nuclear spin entanglement inherent within the material. Here, we demonstrate that a photon quantum state imprinted in polarization is transferred to another photon emitted from a nitrogen vacancy (NV) center. This transfer is heralded by the result of the Bell state measurement between the electron and nitrogen nuclear spins. We show that the minimum number of incident photons needed to achieve transfer is, on average, only 0.1 photons, enabling quantum teleportation over 10 km. This demonstration paves the way for a fault-tolerant quantum repeater that is robust against phase and intensity errors, unlike the conventional photon interference scheme, thereby facilitating practical quantum networks.