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.

数字革命的实现依赖于硅基纳米结构器件。在即将到来的量子时代，硅材料有望复刻其昔日的核心地位：硅纳米加工技术已达到无可匹敌的成熟度，为器件集成与规模化量产提供了独特优势；同时其优异的材料特性可支撑具备小时级相干时长的量子存储器的研制。尽管小型自旋量子比特（spin-qubit）量子寄存器已突破纠错阈值，但如何将其接入大规模量子计算机仍是一项亟待攻克的重大挑战。为此，搭载光学接口的自旋量子比特具备核心优势：可最大限度降低热负载，同时支持模块化量子计算架构——这类架构能够消除串扰，并通过室温光子路由实现大规模互连。本研究基于纳米光子谐振腔（nanophotonic resonator）中的铒掺杂体系，实现了这类高效自旋-光子接口。据此，我们在硅基体系中首次实现了相干时长超过珀塞尔（Purcell）增强光学寿命的自旋光学单次读出，为通过光子干涉实现远程自旋纠缠铺平了道路。