Engineering integrated photonics for heralded quantum gates

Thomas Meany, Devon Biggerstaff, Matthew Broome, Alessandro Fedrizzi , Michael Delanty, M Steel, Alexei Gilchrist, Graham Marshall, Andrew White, Michael Withford

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

20 Citations (Scopus)
301 Downloads (Pure)


Scaling up linear-optics quantum computing will require multi-photon gates which are compact, phase-stable, exhibit excellent quantum interference, and have success heralded by the detection of ancillary photons. We investigate the design, fabrication and characterisation of the optimal known gate scheme which meets these requirements: the Knill controlled-Z gate, implemented in integrated laser-written waveguide arrays. We show device performance to be less sensitive to phase variations in the circuit than to small deviations in the coupler reflectivity, which are expected given the tolerance values of the fabrication method. The mode fidelity is also shown to be less sensitive to reflectivity and phase errors than the process fidelity. Our best device achieves a fidelity of 0.931 ± 0.001 with the ideal 4 × 4 unitary circuit and a process fidelity of 0.680 ± 0.005 with the ideal computational-basis process.
Original languageEnglish
Article number25126
Number of pages8
JournalScientific Reports
Publication statusPublished - 10 Jun 2016

Structured keywords

  • QETLabs


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