Universal linear optics

Jacques Carolan, Christopher Harrold, Chris Sparrow, Enrique Martin Lopez, Nick Russell, Josh Silverstone, Peter Shadbolt, Nobuyuki Matsuda, Manabu Ogama, Mikitaka Itoh, Graham Marshall, Mark Thompson, Jonathan Matthews, Toshikazu Hashimoto, Jeremy O'Brien, Anthony Laing

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

740 Citations (Scopus)
2 Downloads (Pure)


Linear optics underpins fundamental tests of quantum mechanics and quantum technologies. We demonstrate a single reprogrammable optical circuit that is sufficient to implement all possible linear optical protocols up to the size of that circuit. Our six-mode universal system consists of a cascade of 15 Mach-Zehnder interferometers with 30 thermo-optic phase shifters integrated into a single photonic chip that is electrically and optically interfaced for arbitrary setting of all phase shifters, input of up to six photons, and their measurement with a 12-single-photon detector system. We programmed this system to implement heralded quantum logic and entangling gates, boson sampling with verification tests, and six-dimensional complex Hadamards. We implemented 100 Haar random unitaries with an average fidelity of 0.999 ± 0.001. Our system can be rapidly reprogrammed to implement these and any other linear optical protocol, pointing the way to applications across fundamental science and quantum technologies.
Original languageEnglish
Pages (from-to)711-716
Number of pages6
Issue number6249
Early online date9 Jul 2015
Publication statusPublished - 14 Aug 2015

Bibliographical note

The authors acknowledge support from the Engineering and Physical Sciences Research Council (EPSRC), the European Research Council (ERC), including BBOI, QUCHIP (H2020-FETPROACT-3-2014: Quantum simulation), PIQUE (FP7-PEOPLE-2013-ITN), the Centre for Nanoscience and Quantum Information (NSQI), the U.S. Army Research Office (ARO) grant W911NF-14-1-0133, and the U.S. Air Force Office of Scientific Research (AFOSR). J.C.F.M. was supported by a Leverhulme Trust Early Career Fellowship. J.L.O’B. acknowledges a Royal Society Wolfson Merit Award and a Royal Academy of Engineering Chair in Emerging Technologies.

Structured keywords

  • Bristol Quantum Information Institute
  • QETLabs


  • Reprogrammable Optical Chip
  • Linear Optics


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