Quantum theory permits interference between indistinguishable paths but, at the same time, restricts its order. Single-particle interference, for instance, is limited to the second order, that is, to pairs of single-particle paths. To date, all experimental efforts to search for higher-order interferences beyond those compatible with quantum mechanics have been based on such single-particle schemes. However, quantum physics is not bound to single-particle interference. We here experimentally study many-particle higher-order interference using a two-photon-five-slit setup. We observe nonzero two-particle interference up to fourth order, corresponding to the interference of two distinct two-particle paths. We further show that fifth-order interference is restricted to ${10}^{-3}$ in the intensity-correlation regime and to ${10}^{-2}$ in the photon-correlation regime, thus providing novel bounds on higher-order quantum interference.

中文翻译：

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测试具有多粒子状态的高阶量子干涉

量子理论允许在无法区分的路径之间进行干涉，但同时限制了其顺序。例如，单粒子干扰仅限于第二阶，即仅限于成对的单粒子路径。迄今为止，寻找与量子力学兼容的更高阶干扰的所有实验工作都基于这种单粒子方案。但是，量子物理学并不局限于单粒子干涉。我们在这里使用两光子五缝设置实验研究多粒子高阶干涉。我们观察到高达零阶的非零两粒子干涉，对应于两个不同的两粒子路径的干涉。我们进一步表明，五阶干扰仅限于${10}^{-3}$ 在强度相关机制中 ${10}^{-\mathrm{2个}}$ 在光子相关机制中，从而为高阶量子干涉提供了新颖的界限。