Multi-photon absorption limits to heralded single photon sources

Chad A. Husko*, Alex S. Clark, Matthew J. Collins, Alfredo De Rossi, Sylvain Combrie, Gaelle Lehoucq, Isabella H. Rey, Thomas F. Krauss, Chunle Xiong, Benjamin J. Eggleton

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

71 Citations (Scopus)
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Single photons are of paramount importance to future quantum technologies, including quantum communication and computation. Nonlinear photonic devices using parametric processes offer a straightforward route to generating photons, however additional nonlinear processes may come into play and interfere with these sources. Here we analyse spontaneous four-wave mixing (SFWM) sources in the presence of multi-photon processes. We conduct experiments in silicon and gallium indium phosphide photonic crystal waveguides which display inherently different nonlinear absorption processes, namely two-photon (TPA) and three-photon absorption (ThPA), respectively. We develop a novel model capturing these diverse effects which is in excellent quantitative agreement with measurements of brightness, coincidence-to-accidental ratio (CAR) and second-order correlation function g((2))(0), showing that TPA imposes an intrinsic limit on heralded single photon sources. We build on these observations to devise a new metric, the quantum utility (QMU), enabling further optimisation of single photon sources.

Original languageEnglish
Article number3087
Number of pages8
JournalScientific Reports
Publication statusPublished - 4 Nov 2013


  • Crystal wave-guides
  • Self-phase modulation
  • Slow-light
  • Pair generation
  • Correlated photons
  • 2-photon absorption
  • Wavelength conversion
  • Resonator
  • Dispersion
  • Fiber


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