AI 中文总结
研究在城市自由空间信道上分发随时间演化的纠缠态，开发含同步装置的系统，实现两端低于50皮秒计时精度，结果表明可通过有噪声信道可靠传输纠缠，是长距离自由空间量子通信重要基准。
AI 中文摘要
随时间演化的纠缠态描述了量子粒子，其相关性根据明确的动力学随时间演化。此类状态可在多种物理系统中生成，是从量子时钟同步到量子通信等多种量子技术的有前景资源。然而，其全部潜力目前受限于纠缠动力学常发生在与可实现的同步精度相当的时间尺度上，尤其在通过有噪声的城市信道分发纠缠的实验中。在此背景下，精确计时不仅是技术细节，更是忠实观测和利用潜在量子相关性的基本要求。我们展示了在连接罗马市中心两栋建筑的270米自由空间信道上快速演化的纠缠态的可靠分发。所开发系统包含一个同步装置，能在链路两端实现低于50皮秒的计时精度，同时支持信道稳定。我们的结果表明，随时间演化的纠缠可通过有噪声的城市自由空间信道可靠传输，这是迈向长距离自由空间量子通信以及在如基于卫星的量子网络等苛刻场景中未来实现时间相关纠缠态的重要基准。
英文摘要
Time-evolving entangled states describe quantum particles whose correlations evolve in time according to a well-defined dynamics. Such states can be generated in a variety of physical systems and are promising resources for several quantum technologies, ranging from quantum clock synchronization to quantum communication. However, their full potential is currently limited by the fact that the entanglement dynamics often occur on timescales comparable to the achievable synchronization precision, especially in experiments aimed at distributing entanglement through noisy urban channels. In this context, accurate timing is not merely a technical detail, but a fundamental requirement for faithfully observing and exploiting the underlying quantum correlations. Here, we demonstrate the faithful distribution of a fast-evolving entangled state over a 270 m free-space channel connecting two buildings in the center of Rome. The developed system incorporates a synchronization device capable of achieving sub-50 ps timing accuracy between the two ends of the link while simultaneously supporting channel stabilization. Our results demonstrate that time-evolving entanglement can be reliably transmitted through a noisy urban free-space channel, representing an important benchmark toward long-distance free-space quantum communication and the future implementation of time-correlated entangled states in demanding scenarios such as satellite-based quantum networks.
