Researchers from Wits University and Universitat Autònoma de Barcelona show how controlling the structure of photons in space and time enables tailored quantum states for next-generation communication, sensing and imaging. Credit: Wits University

Researchers from the School of Physics at Wits University, working with collaborators from the Universitat Autònoma de Barcelona, have demonstrated how quantum light can be engineered in space and time to create high-dimensional and multidimensional quantum states. Their work highlights how structured photons—light whose spatial, temporal or spectral properties are deliberately shaped—offer new pathways for high-capacity quantum communication and advanced quantum technologies.

Published as a review article in Nature Photonics, the study surveys rapid progress in techniques capable of creating, manipulating and detecting quantum structured light. These include on-chip integrated photonics, nonlinear optics, and multiplane light conversion, which now form a modern and increasingly powerful toolkit. Together, these advances are bringing structured quantum states closer to real-world applications in imaging, sensing, and quantum networks.

Advances in quantum light engineering

According to Professor Andrew Forbes, corresponding author from Wits, the field has changed dramatically in two decades. "The tailoring of quantum states, where quantum light is engineered for a particular purpose, has gathered pace of late, finally starting to show its full potential. Twenty years ago, the toolkit for this was virtually empty. Today we have on-chip sources of quantum structured light that are compact and efficient, able to create and control quantum states."

A key benefit of structuring photons is the ability to access high-dimensional encoding alphabets, enabling more information per photon and greater resilience to noise. This makes quantum structured light a promising platform for secure quantum communication.

Challenges and future directions

However, the authors note that some real-world channels are still unfavorable to spatially structured photons, limiting long-distance transmission compared to more traditional degrees of freedom such as polarization.

"Although we have made amazing progress, there are still challenging issues," says Forbes. "The distance reach with structured light, both classical and quantum, remains very low … but this is also an opportunity, stimulating the search for more abstract degrees of freedom to exploit."

One emerging approach is to imbue quantum states with topological properties, offering inherent robustness to perturbations. "We have recently shown how quantum wave functions naturally have the potential to be topological, and this promises the preservation of quantum information even if the entanglement is fragile," says Forbes.

Applications and outlook for the field

The review article also documents rapid developments in multidimensional entanglement, ultrafast temporal structuring, nonlinear quantum detection schemes, and on-chip sources that can generate or process quantum light at higher dimensions than previously possible. Applications highlighted include high-resolution quantum imaging, precision metrology using structured photons, and quantum networks capable of carrying more information through multiple coupled channels.

The research points to an inflection point for the field. As the authors conclude, the future for quantum optics with quantum structured light "looks very bright indeed"—but further work is needed to increase dimensionality, boost photon numbers, and engineer states that survive realistic optical environments.

More information: Andrew Forbes et al, Progress in quantum structured light, Nature Photonics (2025). DOI: 10.1038/s41566-025-01795-x

Citation: Shaping quantum light unlocks new possibilities for future technologies (2025, December 5) retrieved 5 December 2025 from https://phys.org/news/2025-12-quantum-possibilities-future-technologies.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.