Large-scale silicon quantum photonics implementing arbitrary two-qubit processing

Xiaogang Qiang, Xiaoqi Zhou, Jianwei Wang, Callum Wilkes, Thomas Loke, Sean O'Gara, Laurent Kling, Graham Marshall, Raffaele Santagati, TC Ralph, Jingbo Wang, Jeremy O'Brien, Mark Thompson, Jonathan Matthews*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

249 Citations (Scopus)
513 Downloads (Pure)


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.

Original languageEnglish
Pages (from-to)534-539
Number of pages6
JournalNature Photonics
Issue number9
Early online date20 Aug 2018
Publication statusPublished - Sep 2018


  • quant-ph


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