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Quantum photonics passes integration milestone

Microscope image of the device at the centre of this work. Thin lines are wave-guides; thick lines are electrical wires. A white scale bar indicates 0.1 mm.

10 August 2015

CQP Researchers bring chip-scale quantum devices closer to reality in new article in Nature Communications this month.

The team of researchers led by Prof. Mark Thompson at Bristol’s Centre for Quantum Photonics have added new photon-colour leveraging tools to the quantum photonic engineer’s toolbox. By combining high-performance silicon photonics—the same technology pursued by microelectronics heavyweights for on-chip optical interconnects—and quantum optics, the team was able to integrate the production of spectrally structured and entangled light, and its analysis, within a device measuring less than a millimetre in length.

 Sources of photon-pairs, based on silicon microring resonators, could one day produce large and exotic states of light—the raw materials for quantum applications with photons—on-chip. The spectrally structured photons which they produce, however, have until now been a challenge to control. By using a second microring resonator, acting as a demultiplexer, the Bristol researchers were able to precisely control and analyse the photons’ spectral properties. To test their new device, the team entangled the on-chip photon pairs, and used their entanglement as a hallmark of the device’s excellent performance.

This work was published in Nature Communications, on 6 August 2015.

Further information

Read the full article: J. W. Silverstone, R. Santagati, D. Bonneau, M. J. Strain, M. Sorel, J. L. O’Brien & M. G. Thompson, “Qubit entanglement between ring-resonator photon-pair sources on a silicon chip”, Nature Communications 6, Article number: 7948 (2015) doi:10.1038/ncomms8948 (

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