AI 中文总结
研究金刚石中锡空位自旋量子比特产生高度不可区分光子，通过分离特性与缺陷展示其优势，结合长寿命相干时间，经模拟证实该平台在长距离量子网络及光子量子信息处理方面有竞争力，超越直接传输界限。
AI 中文摘要
量子网络有望通过光子链路连接远距离量子节点，实现安全通信、分布式传感和模块化量子计算。将此类网络扩展到城域距离之外需要量子中继器来克服光纤中光子的指数衰减。在所有架构中，一个关键要求是单光子的不可区分性，这直接影响基于双光子干涉的光子操作的保真度。在此，我们展示了从金刚石中相干激发的锡空位中心产生高度不可区分的单光子，实现了超过0.95的原始Hong-Ou-Mandel干涉可见度。通过将本征发射体特性与技术缺陷分离，我们表明退相干起的作用可忽略不计，其余限制主要是技术性的，本征不可区分性高达0.999。我们还表明，量子频率转换到电信C波段可保持光子的不可区分性。结合长寿命的电子和核自旋相干时间，这些结果确立了金刚石中的锡空位中心作为长距离量子网络和光子量子信息处理的有竞争力平台。我们通过量子中继器链路的蒙特卡罗模拟进一步证实了这一潜力，表明SnV中心平台超过了直接传输设定的界限。
英文摘要
Quantum networks promise secure communication, distributed sensing and modular quantum computing by interconnecting distant quantum nodes through photonic links. Extending such networks beyond metropolitan distances requires quantum repeaters to overcome the exponential attenuation of photons in optical fiber. Across all architectures, a key requirement is the indistinguishability of single photons, which directly impacts the fidelity of photonic operations based on two-photon interference, such as Bell-state measurements and fusion gates. Here, we demonstrate generation of highly indistinguishable single photons from a coherently excited tin-vacancy center in diamond, achieving raw Hong-Ou-Mandel interference visibilities exceeding 0.95. By separating intrinsic emitter properties from technical imperfections, we show that decoherence plays a negligible role and that the remaining limitations are predominantly technical in nature, arriving at an intrinsic indistinguishability of up to 0.999. We further show that quantum frequency conversion to the telecom C-band preserves the photon indistinguishability. In combination with the long-lived electron and nuclear spin coherence times, these results establish tin-vacancy centers in diamond as a competitive platform for long-distance quantum networks and photonic quantum information processing. We further substantiate this potential through Monte Carlo simulations of a quantum-repeater link, demonstrating that the SnV-center platform surpasses the bound set by direct transmission.
