标题： 具有反向传播光子的量子非线性光学 显示英文标题

标题： Quantum nonlinear optics with counter-propagating photons

摘要： 实现单光子之间的强相互作用是推进光子量子计算和量子非线性光学发展的基石。 在这里，我们通过里德堡极化子介导，实验演示了反向传播光子之间的强相互作用，实现了超过$1~\mu s$的反相关范围记录。 这种扩展的范围使得能够使用足够长以适应极化子带宽的光子脉冲，同时又足够短以保持在相互作用范围内。 在这些条件下，我们观察到整个脉冲的完全光子阻塞，并且可以通过脉冲定时进行调节，从而展示了可控、确定性操作的潜力。 扩展到三光子体系，当一个光子遇到两个反向传播的光子时，我们观察到增强的相互作用。 我们的研究结果得到了解析理论和严格的数值模拟的支持，确立了反向传播的里德堡极化子作为工程量子光场相互作用的强大平台。 显示英文摘要

摘要： Realizing strong interactions between individual photons is a cornerstone for advancing photonic quantum computing and quantum nonlinear optics. Here, we experimentally demonstrate strong interactions between counter-propagating photons mediated by Rydberg polaritons, achieving a record-long anti-correlation range exceeding $1~\mu s$. This extended range enables the use of photon pulses that are long enough to fit within the polariton bandwidth, yet short enough to remain within the interaction range. Under these conditions, we observe complete photon blockade of entire pulses, tunable by the pulse timing, thus demonstrating the potential for controlled, deterministic operations. Extending to the three-photon regime, we observe enhanced interactions when a photon encounters two counter-propagating photons. Our results, supported by analytical theory and rigorous numerical simulations, establish counter-propagating Rydberg polaritons as a powerful platform for engineering interactions in quantum light fields.