First Direct Measurement of Stokes-Gell-Mann Parameters for Three-Mode Light Achieved on Photonic Chip
Researchers have demonstrated the first direct measurement of the Stokes-Gell-Mann (SGM) parameters for partially coherent three-mode light using a photonic integrated circuit. The SGM parameters, derived from Gell-Mann matrices originally developed in high-energy particle physics, extend the classical two-mode Stokes framework to describe optical fields spanning three modes. This advance opens new possibilities for multimode partially coherent light in optical communications, sensing, and information processing.
A research team has reported the first experimental measurement of the Stokes-Gell-Mann (SGM) parameters for partially coherent three-mode optical fields, published as a preprint on arXiv. The standard Stokes parameters, which rely on 2×2 Pauli matrices, are limited to two-mode optical fields such as polarization pairs, and cannot characterize three-mode fields — such as the full polarization of non-paraxial light or fields with three spatial or temporal modes. The new work employs a photonic integrated platform built from a hexagonal mesh of Mach-Zehnder interferometers to measure all eight SGM expansion coefficients of the 3×3 coherence matrix on chip. From these measurements, the team reconstructed the full coherence matrix, enabling exploration of iso-entropy field spaces — identifying which three-mode fields can be interconverted unitarily and which cannot, despite sharing the same entropy. While the theoretical framework using Gell-Mann matrices has existed for some time, the measurement procedure was previously considered too daunting to implement, making this experimental realization a significant milestone in quantum and classical optics.
What's missing
As a preprint, this work has not yet undergone formal peer review. The paper does not specify the range of coherence states or signal-to-noise conditions tested, leaving open questions about measurement robustness and scalability to fields with more than three modes.
What different sources said
- arXiv physicsCenter
On-chip measurement of the modal Stokes-Gell-Mann parameters for partially coherent three-mode light
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