Person:

Sukachev, Denis

The negatively-charged silicon-vacancy (SiV−) center in diamond is a bright source of indistinguishable single photons and a useful resource in quantum information protocols. Until now, SiV− centers with narrow optical linewidths and small inhomogeneous distributions of SiV− transition frequencies have only been reported in samples doped with silicon during diamond growth. We present a technique for producing implanted SiV− centers with nearly lifetime-limited optical linewidths and a small inhomogeneous distribution. These properties persist after nanofabrication, paving the way for incorporation of high-quality SiV− centers into nanophotonic devices.

Freestanding diamond nanostructures are etched from a bulk diamond substrate and integrated with evanescently coupled superconduncting nanowire single-photon detectors.

The ability to communicate quantum information over long distances is of central importance in quantum science and engineering. While some applications of quantum communication such as secure quantum key distribution (QKD) are already being successfully deployed, their range is currently limited by photon losses and cannot be extended using straightforward measure-and-repeat strategies without compromising unconditional security. Alternatively, quantum repeaters, which utilize intermediate quantum memory nodes and error correction techniques, can extend the range of quantum channels. However, their implementation remains an outstanding challenge, requiring a combination of efficient and high-fidelity quantum memories, gate operations, and measurements. Here we use a single solid-state spin memory integrated in a nanophotonic diamond resonator to implement asynchronous photonic Bell-state measurements, a key component of quantum repeaters. In a proof-of-principle experiment, we demonstrate high-fidelity operation that effectively enables quantum communication at a rate that surpasses the ideal loss-equivalent direct-transmission method while operating at megahertz clock speeds. These results represent a significant step towards practical quantum repeaters and large-scale quantum networks.