Frequency-bin quantum information encoding offers an intriguing synergy with classical optical networks, with the ability to support many qubits in a single fiber. Yet, coherent quantum frequency operations prove extremely challenging due to the difficulties in mixing frequencies arbitrarily and with low noise. In this paper, we address such challenges and implement distinct quantum gates in parallel on two entangled frequency-bin qubits in the same optical fiber. Our basic quantum operation controls the spectral overlap between adjacent spectral bins, allowing us to observe frequency-bin Hong–Ou–Mandel interference with a visibility of $0.971\pm 0.007$. By integrating this tunability with frequency parallelization, we synthesize independent gates on entangled qubits and flip their spectral correlations, allowing us to observe strong violation of the separability bound. Our realization of closed, user-defined gates on frequency-bin qubits in parallel should find application in the development of fiber-compatible quantum information processing and quantum networks.

中文翻译：

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频点比特的量子干扰和相关控制

频点量子信息编码提供了与经典光学网络的有趣协同作用，并能够在单根光纤中支持许多qubit。然而，由于任意混合频率和低噪声的困难，相干量子频率操作被证明是极具挑战性的。在本文中，我们解决了这些挑战，并在同一根光纤中的两个纠缠的频点量子位上并行实现了不同的量子门。我们的基本量子操作控制了相邻光谱仓之间的光谱重叠，使我们能够以可见度观察频仓Hong–Ou–Mandel干扰。$0.971\pm 0.007$。通过将这种可调谐性与频率并行化集成在一起，我们可以在纠缠的量子比特上合成独立的门，并翻转它们的频谱相关性，从而使我们能够观察到强烈违反可分离性界限的情况。我们在频点量子位上并行实现用户定义的封闭门的实现，应在光纤兼容量子信息处理和量子网络的开发中找到应用。