Photonic hyperentanglement, which involves photons simultaneously entangled in more than one degree of freedom (DOF), has many important applications in quantum information processing, especially in high-capacity quantum communications. Interestingly, single-photon qubits encoded in the time-bin DOF are robust for long-distance transmissions in noisy channels. In this paper, we present a hyperentangled-Bell-state generation (HBSG) scheme for preparing two-photon six-qubit states which are simultaneously entangled in the polarization, spatial-mode, and time-bin DOFs. Compared with previous HBSG schemes, we construct an error-detected circuit unit with a quantum-dot (QD) spin in a double-sided optical microcavity, with which errors due to imperfect interactions between photons and QD systems can be easily detected, so that the error-detected circuit unit can relax the experimental requirement and improve the fidelity of our scheme largely. Meanwhile, our scheme is used to prepare two-photon hyperentangled states in polarization-spatial-time three DOFs, which is significant for faithful entanglement distribution and quantum repeater. These features make our scheme more feasible and useful in high-capacity and long-distance quantum communications with hyperentanglement.

中文翻译：

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由量子点自旋辅助的极化时空三自由度中高保真光子超纠缠的误差检测生成

光子超纠缠涉及在一个以上自由度 (DOF) 中同时纠缠的光子，在量子信息处理中具有许多重要应用，尤其是在大容量量子通信中。有趣的是，在时间仓 DOF 中编码的单光子量子位对于噪声通道中的长距离传输是稳健的。在本文中，我们提出了一种超纠缠贝尔态生成 (HBSG) 方案，用于制备同时纠缠在偏振、空间模式和时间仓自由度中的双光子六量子位态。与之前的 HBSG 方案相比，我们在双面光学微腔中构建了一个带有量子点 (QD) 自旋的误差检测电路单元，可以很容易地检测到由于光子和 QD 系统之间不完美的相互作用引起的误差，使得错误检测电路单元可以放宽实验要求，并在很大程度上提高我们方案的保真度。同时，我们的方案用于在偏振时空三自由度中制备双光子超纠缠态，这对于忠实纠缠分布和量子中继器具有重要意义。这些特性使我们的方案在具有超纠缠的大容量和长距离量子通信中更加可行和有用。