What Happens When Light Gains Extra Dimensions
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By sculpting light into complex quantum forms, scientists are unlocking new ways to transmit information, compute faster, and see more clearly. The technology is now mature enough to move beyond the lab and into practical applications. Credit: SciTechDaily.com Shaped quantum light is turning ordinary photons into powerful tools for the future of technology. A global group of scientists, including researchers from the UAB, has published a new review in Nature Photonics exploring a rapidly developing area of research called quantum structured light. This field is changing how information can be sent, measured, and processed by combining quantum physics with carefully designed patterns of light in space and time. By doing so, researchers can create photons capable of carrying far more information than traditional light. From Qubits to Higher Dimensional Quantum States The review explains that light can be controlled through several properties at once, including polarization, spatial modes, and frequency. By manipulating these different degrees of freedom, scientists can generate high-dimensional quantum states. In these systems, familiar qubits (two-dimensional, with photons in superposition of two quantum states) are replaced by qudits (with more than two dimensions). This shift greatly expands the range of possibilities for quantum technologies. In quantum communication, these high-dimensional photons improve security because each photon can carry more information. They also make it possible to run many communication channels at the same time while improving resistance to errors and background noise. For quantum computing, structured light allows for simpler and faster circuit designs and makes it easier to create the complex quantum states needed for advanced simulations. New Opportunities in Imaging and Measurement Quantum structured light is also opening new paths in imaging and metrology. The authors point to major improvements in resolution techniques, including the recent development of the holographic quantum microscope, which allows obtaining images of delicate biological samples. The approach also supports the creation of extremely sensitive sensors that rely on quantum correlations. Beyond imaging and sensing, structured light can be used to simulate complex quantum systems. These simulations can help researchers predict how molecules interact within networks, an ability that could support the discovery and design of new materials.
Rapid Progress Over Two Decades Professor Andrew Forbes, corresponding author from the University of the Witwatersrand, at Johannesburg, says the field has evolved dramatically over the past twenty years. “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.” Despite this progress, challenges remain. “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.” From Research Curiosity to Practical Impact According to researcher Adam Vallés from the Optics Group of the UAB Department of Physics, the field has reached a critical moment. “We are at a turning point: quantum structured light is no longer just a scientific curiosity, but a tool with real potential to transform communication, computing and image processing.” Vallés also highlights UAB’s leading role in this area through its collaboration with Forbes, pointing to “advances of great international impact, such as the stimulated teleportation of quantum information encoded in high dimensions, the design of laser cavities to generate complex states of high purity and, in the field of cryptography, the distribution of robust quantum keys in the face of obstacles that block communication channels.” Reference: “Progress in quantum structured light” by Andrew Forbes, Fazilah Nothlawala and Adam Vallés, 21 November 2025, Nature Photonics. DOI: 10.1038/s41566-025-01795-x The review, which appears as the cover article in this month’s issue of Nature Photonics, reflects a long-running collaboration between Vallés and the structured light research group led by Forbes at the Faculty of Physics of the University of the Witwatersrand in Johannesburg, South Africa. The work was also supported by the Catalonia Quantum Academy (CQA), a collaborative initiative coordinated by the Institut de Ciències Fotòniques (ICFO) and promoted by the Government of Catalonia. The academy focuses on strengthening education and talent development in quantum sciences and technologies across Catalonia.