Topological photonics provide a promising way to realize more robust optical devices against some defects and environmental perturbations. Quantum logic gates are fundamental units of quantum computers, which are widely used in future quantum information processing. Thus, constructing robust universal quantum logic gates is an important way forward to practical quantum computing. However, the most important problem to be solved is how to construct the quantum-logic-gate-required 2 × 2 beam splitter with topological protection. Here, the experimental realization of the topologically protected contradirectional coupler is reported, which can be employed to realize the quantum logic gates, including control-NOT and Hadamard gates, on the silicon photonic platform. These quantum gates not only have high experimental fidelities but also exhibit a certain degree of tolerances against certain types of defects. This work paves the way for the development of practical optical quantum computations and signal processing.

中文翻译：

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采用 Valley-Hall 光子晶体的拓扑保护量子逻辑门

拓扑光子学提供了一种有前途的方法来实现更鲁棒的光学器件，以应对某些缺陷和环境扰动。量子逻辑门是量子计算机的基本单元，广泛应用于未来的量子信息处理。因此，构建鲁棒的通用量子逻辑门是实现实用量子计算的重要途径。然而，最重要的问题是如何构造量子逻辑门所需的具有拓扑保护的2×2分束器。本文报道了拓扑保护反向耦合器的实验实现，该耦合器可用于在硅光子平台上实现量子逻辑门，包括控制非门和哈达玛门。这些量子门不仅具有高实验保真度，而且对某些类型的缺陷表现出一定程度的容忍度。这项工作为实用光量子计算和信号处理的发展铺平了道路。