Production and analysis of qubit entanglement on a silicon photonic chip

Josh Silverstone, Raffaele Santagati, Damien Bonneau, Michael J Strain, Marc Sorel, Mark G Thompson

Research output: Contribution to conferenceConference Abstractpeer-review

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Silicon quantum photonics promises to take quantum optics to the large scale, where single photons carry the quantum information which can accelerate difficult computational problems, provide perfectly secure communication, or allow high-accuracy measurements. The silicon photonics platform offers miniature, high-yield, and high-performance photonics which are integrable with CMOS electronics and telecommunications-band optics.

To date, only non-scalable photon-pair sources, based on spontaneous four-wave mixing (SFWM) in straight silicon waveguides have been shown to interfere [1]. Until now, single-photon experiments in silicon [2] have exclusively used an off-chip apparatus, such as a silica arrayed waveguide grating, to control and manipulate photon frequency. We present a silicon-on-insulator quantum photonic device (Fig. 1a) able to generate and analyse two maximally entangled qubits. We use this device to demonstrate high-visibility quantum interferencebetween resonant SFWM sources (analogous to [1]), phase-stable frequency-selection, and quantum state tomography.

We varied the phase  to obtain the fringes shown in Fig. 1b, with a visibility of 96.8%. This high visibility indicates that the two microring sources are substantially identical. We setup the entangled state via the on-chip 17-dB extinction filters, and used quantum state tomography to analyse it (Fig. 1c). We measured a fidelity of 0.8.

This is the first time an entangled state of photonic qubits has been both generated and analysed on-chip, and this generation has been done in a way which is scalable to larger photon number. These results represent a new step towards fully silicon-integrated quantum photonics.
Original languageEnglish
Number of pages1
Publication statusPublished - Sept 2014
EventPhoton 14 - Imperial College, London, United Kingdom
Duration: 1 Sept 20144 Sept 2014


ConferencePhoton 14
Country/TerritoryUnited Kingdom

Structured keywords

  • QETLabs
  • Photonics and Quantum


  • Quantum photonics
  • quantum optics


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