Photonics is a promising platform for implementing universal quantum information processing. Its main challenges include precise control of massive circuits of linear optical components and effective implementation of entangling operations on photons. By using large-scale silicon photonic circuits to implement an extension of the linear combination of quantum operators scheme, we realize a fully programmable two-qubit quantum processor, enabling universal two-qubit quantum information processing in optics. The quantum processor is fabricated with mature CMOS-compatible processing and comprises more than 200 photonic components. We programmed the device to implement 98 different two-qubit unitary operations (with an average quantum process fidelity of 93.2 ± 4.5%), a two-qubit quantum approximate optimization algorithm, and efficient simulation of Szegedy directed quantum walks. This fosters further use of the linear-combination architecture with silicon photonics for future photonic quantum processors.

光子学是用于实现通用量子信息处理的有前途的平台。它的主要挑战包括精确控制线性光学组件的大规模电路以及在光子上有效实施纠缠操作。通过使用大规模硅光子电路来实现量子算子方案线性组合的扩展，我们实现了一个完全可编程的二量子位量子处理器，从而实现了光学中的通用二量子位量子信息处理。量子处理器采用成熟的CMOS兼容工艺制造，包括200多个光子组件。我们对该设备进行了编程，以实现98种不同的二量子位unit元运算（平均量子过程​​保真度为93.2±4.5％），一种二量子位量子近似优化算法，和塞格迪定向量子行走的高效仿真。这促进了将线性组合架构与硅光子技术进一步用于未来的光子量子处理器。