Heralded quantum-entanglement transfer based on photon absorption of nitrogen-vacancy centers in diamond

As a kind of hybrid spin system, nitrogen-vacancy (NV) centers in diamond have shown great advantages in implementing quantum registers for quantum information processing (QIP). When scaling up quantum registers to quantum networks for long-distance quantum communication and distributed quantum computation, determining how to entangle two registers in distant nodes is a basic challenge in the absence of direct interactions. In this paper, we present a scheme for entangling two distantNVcenters based on the special optical absorption and emission ofNVcenters. In this demonstration, we transfer the entanglement information of a pair of photons to nuclear spins in NV centers and create remote NV-NV entanglement mediated by entangled photons. We then explain how to extract the entangled information from NV centers to prepare on-demand entangled photons for optical quantum information processing. The strategy of entanglement transfer between spins and photons demonstrated herein may pave the way for anNV-center-based quantum network. (C) 2021 Optical Society of America.