Hong Ling, Zhang Yuning, Chen Yuanyuan, Chen Lixiang
Department of Physics, <a href="https://ror.org/00mcjh785">Xiamen University</a>, Xiamen 361005, China.
Phys Rev Lett. 2024 Jul 12;133(2):023601. doi: 10.1103/PhysRevLett.133.023601.
Hong-Ou-Mandel interference is an intrinsic quantum phenomenon that goes beyond the possibilities of classical physics, and enables numerous applications in quantum information science. While the photon-photon interaction is fundamentally limited to the bosonic nature of photons and the restricted phase responses from commonly used unitary optical elements, we present that a nonunitary material provides an alternative degree of freedom to control the two-photon quantum interference, even revealing anomalous quantum interference paths that do not exist in a unitary configuration. An elaborate lossy multilayer graphene that can work as a nonunitary beam splitter is used to explore its tunability over the effective photon-photon interaction in spatial modes, and to verify the particle exchange statistics by its experimental implementation in quantum state filter. This scheme is further extended to observe four-dimensional quantum interference patterns on the lossless and lossy beam splitters, and thus show its applicability even in higher-dimensional Hilbert space.
Hong-Ou-Mandel干涉是一种超越经典物理可能性的内在量子现象，在量子信息科学中有众多应用。虽然光子-光子相互作用从根本上受限于光子的玻色子性质以及常用幺正光学元件的受限相位响应，但我们发现非幺正材料提供了另一种控制双光子量子干涉的自由度，甚至揭示了在幺正配置中不存在的异常量子干涉路径。一种精心设计的有损多层石墨烯可作为非幺正分束器，用于探索其对空间模式中有效光子-光子相互作用的可调性，并通过在量子态滤波器中的实验实现来验证粒子交换统计。该方案进一步扩展以观察无损和有损分束器上的四维量子干涉图案，从而表明其即使在高维希尔伯特空间中也具有适用性。
