A team of scientists has unlocked a new frontier in quantum imaging, using a nanoscale metasurface to generate entangled photon pairs with unmatched resolution and tunability.
This breakthrough eliminates mechanical scanning, making ultra-fast, compact quantum imaging systems a reality. The implications stretch from LiDAR to secure communication, bringing us closer to real-world quantum applications.
Revolutionizing Quantum Imaging with Metasurfaces
Scientists from the ARC Centre of Excellence for Transformative Meta-Optical Systems (TMOS) at the Australian National University (ANU) and the University of Melbourne (UoM) have developed a groundbreaking quantum imaging technique. Their method uses spatially entangled photon pairs generated by an ultra-thin nonlinear metasurface, allowing for high-resolution image reconstruction through a combination of ghost imaging and all-optical scanning. This breakthrough represents a major advancement in quantum optics and imaging technology.
Published in eLight, the study addresses key limitations of traditional quantum imaging, which relies on bulky nonlinear crystals. These conventional systems suffer from restricted size, narrow angular emission, and limited field of view, making them impractical for many real-world applications. To overcome these challenges, the TMOS team designed a nanoscale silica meta-grating integrated with a thin lithium niobate film. This compact structure efficiently generates entangled photon pairs while providing a highly tunable and scalable platform for quantum imaging.
Innovative Optical Scanning Without Mechanical Components
“A key innovation of the study lies in the ability to manipulate photon emission angles all optically by simply tuning the wavelength of the pump beam. This unique property eliminates the need for mechanical scanning, allowing seamless and precise optical scanning in one dimension while maintaining broad anti-correlated photon emissions in the other,” said co-lead author Jinliang Ren, PhD student at TMOS, ANU.
Using these features, the researchers successfully combined optical scanning with ghost imaging to reconstruct two-dimensional objects. This approach uses a simple one-dimensional detector array in the idler path and a bucket detector in the signal path, dramatically reducing the hardware requirements compared to conventional systems.
Experimental Validation and Unmatched Performance
The researchers experimentally validated their method by reconstructing images of two-dimensional objects at infrared wavelengths and predicted a significant improvement in both resolution and field of view. They found that the number of resolution cells achieved by their metasurface-based imaging system can exceed conventional quantum ghost imaging setups by over four orders of magnitude. This remarkable performance stems from the absence of longitudinal phase-matching constraints, which limit the field of view in conventional bulk crystals.
Metasurfaces: The Future of Quantum Imaging?
Dr. Jinyong Ma, the study’s lead researcher, highlighted the potential impact of this innovation. “Our work demonstrates the first practical potential of metasurface-based quantum imaging systems for real-world applications. Their compact design and tunability make them ideal for free-space applications, where size, stability, and scalability are critical. This technology enables integration into modern photonics systems, paving the way for advancements in free-space quantum communication, object tracking, and sensing applications.” Furthermore, performing optical scanning without mechanical components allows for ultra-fast imaging, essential for dynamic imaging scenarios such as quantum LiDAR and object tracking.
Looking ahead, the researchers are exploring ways to further enhance the photon pair generation efficiency of metasurfaces. “We are investigating new materials with higher nonlinear coefficients and optimizing the metasurface design for triple resonances at the pump, signal, and idler wavelengths, which can potentially achieve photon-pair generation rates comparable to or exceeding those of conventional bulky systems. This development will significantly improve the speed, sensitivity, and signal-to-noise ratio of metasurface-based quantum imaging systems, bringing them closer to widespread practical use.” said co-author Dr. Jihua Zhang, a former TMOS research fellow who recently moved to Songshan Lake Materials Laboratory.
Beyond Imaging: Expanding the Scope of Quantum Technologies
“The implications of this work extend beyond imaging alone. Quantum technologies relying on entangled photon pairs, such as secure communication networks, quantum LiDAR, and advanced sensing systems, could benefit from the compact, highly efficient photon-pair sources enabled by nonlinear metasurfaces. Combining optical tunability, nanoscale integration, and high-resolution imaging provides a versatile platform for a wide range of quantum applications,” said Professor Andrey Sukhorukov, the leader of the research group.
A New Era for Quantum Optics
This research represents a major milestone in quantum optics and highlights the transformative potential of metasurface-based technologies. By replacing bulky and rigid optical components with scalable, ultra-thin structures, the TMOS team has laid the foundation for a new generation of quantum imaging and sensing devices that are more compact, efficient, and adaptable than ever.
Reference: “Quantum imaging using spatially entangled photon pairs from a nonlinear metasurface” by Jinyong Ma, Jinliang Ren, Jihua Zhang, Jiajun Meng, Caitlin McManus-Barrett, Kenneth B. Crozier and Andrey A. Sukhorukov, 10 February 2025, eLight.
DOI: 10.1186/s43593-024-00080-8
