发表机构
Center for Theoretical Physics & School of Physics and Optoelectronic Engineering, Hainan University; Department of Microtechnology and Nanoscience, Chalmers University of Technology（海南大学理论物理中心与物理光电工程学院; 查尔姆斯理工大学微技术与纳米科学系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究提出巨原子分束器作为可编程HOM干涉仪，通过耦合相位调节实现单光子分束与双光子干涉的连续控制，并用于量子参数估计，为量子信息处理提供新平台。
AI 中文摘要
Hong--Ou--Mandel（HOM）效应是双光子量子干涉的标志性现象，其中两个不可区分的光子入射到平衡分束器上时，会聚束到同一输出端口。在此，我们展示了一个巨原子（GA），通过两个耦合点分别与两条波导耦合，可以充当可编程的HOM干涉仪，实现对单光子分束和双光子干涉的连续控制。这种可编程性源于巨原子中的耦合相位差，它调节巨原子的自干涉和方向性，从而调节其散射响应。为了表征双光子干涉，我们分析了通过不同波导注入的两个高斯单光子波包的散射，并评估了四个输出端口的聚束和反聚束（符合）概率。在巨原子对单光子表现为有效50:50分束器的工作点上，我们观察到随着两个波包之间相对输入延迟的变化，出现显著的HOM凹陷。偏离该点时，调节耦合相位可连续地调节双光子输出统计，使其在聚束到同一输出端口和反聚束到不同输出端口之间变化。此外，我们探索了其在量子参数估计中的应用，表明可以从双光子输出统计中估计耦合相位的微小偏差，其可达到的灵敏度由与二元符合测量相关的经典Fisher信息量化。因此，我们的巨原子分束器为波导量子电动力学中的双光子干涉提供了一个可编程平台，在量子信息处理、量子通信和量子传感方面具有潜在应用。
英文摘要
The Hong--Ou--Mandel (HOM) effect is a hallmark of two-photon quantum interference, in which two indistinguishable photons impinging on a balanced beam splitter bunch into the same output port. Here, we show that a giant atom (GA), coupled to two waveguides through two coupling points each, can function as a programmable HOM interferometer, enabling continuous control over single-photon beam splitting and two-photon interference. This programmability arises from coupling-phase differences in the GA, which tune its self-interference and directionality, and thereby its scattering response. To characterize the two-photon interference, we analyze the scattering of two Gaussian single-photon wave packets injected through different waveguides and evaluate the bunching and antibunching (coincidence) probabilities of the resulting four output ports. At the operating point where the GA acts as an effective 50:50 beam splitter for single photons, we observe a pronounced HOM dip as the relative input delay between the two wave packets is varied. Away from this point, adjusting the coupling phases continuously tunes the two-photon output statistics between bunching into the same output port and antibunching across distinct output ports. In addition, we explore an application to quantum parameter estimation, showing that small deviations of coupling phases can be estimated from the two-photon output statistics, with the achievable sensitivity quantified by the classical Fisher information associated with a binary coincidence measurement. Our giant-atom beam splitter thus provides a programmable platform for two-photon interference in waveguide quantum electrodynamics, with potential applications in quantum information processing, quantum communication, and quantum sensing.
