Entangled ripples and twists of light: Radial and azimuthal Laguerre-Gaussian mode entanglement

Natalia Herrera Valencia*, Vatshal Srivastav, Saroch Leedumrongwatthanakun, Will McCutcheon, Mehul Malik

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)
17 Downloads (Pure)


It is well known that photons can carry a spatial structure akin to a 'twisted' or 'rippled' wavefront. Such structured light fields have sparked significant interest in both classical and quantum physics, with applications ranging from dense communications to light-matter interaction. Harnessing the full advantage of transverse spatial photonic encoding using the Laguerre-Gaussian (LG) basis in the quantum domain requires control over both the azimuthal (twisted) and radial (rippled) components of photons. However, precise measurement of the radial photonic degree-of-freedom has proven to be experimentally challenging primarily due to its transverse amplitude structure. Here we demonstrate the generation and certification of full-field LG entanglement between photons pairs generated by spontaneous parametric down conversion in the telecom regime. By precisely tuning the optical system parameters for state generation and collection, and adopting recently developed techniques for precise spatial mode measurement, we are able to certify fidelities up to 85% and entanglement dimensionalities up to 26 in a 43-dimensional radial and azimuthal LG mode space. Furthermore, we study two-photon quantum correlations between nine LG mode groups, demonstrating a correlation structure related to mode group order and inter-modal cross-talk. In addition, we show how the noise-robustness of high-dimensional entanglement certification can be significantly increased by using measurements in multiple LG mutually unbiased bases. Our work demonstrates the potential offered by the full spatial structure of the two-photon field for enhancing technologies for quantum information processing and communication.

Original languageEnglish
Article number104001
JournalJournal of Optics
Issue number10
Early online date8 Sept 2021
Publication statusPublished - Oct 2021


  • entanglement certification
  • high-dimensional entanglement
  • Laguerre-Gaussian

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics


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