Cluster states are key resources for measurement-based quantum information processing. Photonic cluster and graph states, in particular, play indispensable roles in quantum network and quantum metrology. We demonstrate a semiconductor quantum dot based device in which the confined hole spin acts as a needle in a quantum knitting machine producing continuously and deterministically at sub-Gigahertz repetition rate single indistinguishable photons which are all polarization entangled to each other and to the spin in a one dimensional cluster state. By projecting two nonadjacent photons onto circular polarization bases we disentangle the spin from the photons emitted in between. This way we demonstrate a novel way for producing deterministic and continuous all-photonic cluster states. We use polarization tomography on four sequentially detected photons to demonstrate and to directly quantify the robustness of the cluster’s entanglement and the determinism in its photon generation.

中文翻译：

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不可区分光子的连续且确定性的全光子团簇状态


簇状态是基于测量的量子信息处理的关键资源。特别是光子团簇和图态在量子网络和量子计量中发挥着不可或缺的作用。我们演示了一种基于半导体量子点的器件，其中受限孔自旋充当量子针织机中的针，以亚千兆赫兹重复率连续且确定性地产生单个不可区分的光子，这些光子全部偏振地彼此纠缠并与自旋纠缠。一维簇状态。通过将两个不相邻的光子投射到圆偏振基座上，我们将自旋与之间发射的光子分开。通过这种方式，我们展示了一种产生确定性和连续的全光子簇状态的新方法。我们对四个连续检测到的光子使用偏振断层扫描，以证明并直接量化星团纠缠的鲁棒性及其光子生成的决定论。