Optical single-shot readout of spin qubits in silicon

The digital revolution was enabled by nanostructured devices made from silicon. A similar prominence of this material is anticipated in the upcoming quantum era as the unrivalled maturity of silicon nanofabrication offers unique advantages for integration and up-scaling, while its favorable material properties facilitate quantum memories with hour-long coherence. While small spin-qubit registers have exceeded error-correction thresholds, their connection to large quantum computers is an outstanding challenge. To this end, spin qubits with optical interfaces offer key advantages: they can minimize the heat load and give access to modular quantum computing architectures that eliminate cross-talk and offer a large connectivity via room-temperature photon routing. Here, we implement such an efficient spin-photon interface based on erbium dopants in a nanophotonic resonator. We thus demonstrate optical single-shot readout of a spin in silicon whose coherence exceeds the Purcell-enhanced optical lifetime, paving the way for entangling remote spins via photon interference.