A groundbreaking advancement in quantum computing has emerged with researchers discovering a revolutionary method for creating entangled photons using metasurfaces — engineered flat structures that precisely control light. This innovation promises to overcome one of quantum computing’s persistent challenges by generating and manipulating entangled photons more efficiently and compactly than ever before.
The breakthrough comes from a collaboration between Peking University, Southern University of Science and Technology, and the University of Science and Technology of China, as published in Advanced Photonics Nexus. Their technique employs metasurfaces to create multiphoton entanglement on a single surface, dramatically simplifying what has traditionally required complex optical arrangements.
Quantum information processing depends on photon entanglement to process vast quantities of data. However, conventional methods have significant limitations — quantum nonlinear processes struggle with scalability, while linear beam-splitting approaches require intricate setups vulnerable to signal loss and interference.
The new approach directs single photons toward a specially designed gradient metasurface from multiple angles. These photons undergo quantum interference, producing various entangled states. Remarkably, the technique also enables the fusion of entangled photon pairs into larger, more complex groups, allowing greater quantum information encoding in reduced space.
“It’s like finding a shortcut in a maze,” explains Professor Ying Gu, the study’s corresponding author. “Instead of navigating complex optical setups, we can use a single metasurface. The process becomes much simpler and more compact—perfect for building tiny quantum devices that could fit on a chip.”
The implications extend beyond computing. Metasurfaces could generate and deliver entangled photons to multiple users, facilitating quantum networks. They might also serve as fundamental components for handling increased numbers of photons, potentially leading to laptop-sized quantum computers.
This advancement represents a significant step toward practical quantum technologies, offering a path to more accessible quantum applications through the elegant manipulation of light at the nanoscale—a promising direction for the future of quantum information science.
Reference: “Multiphoton path-polarization entanglement through a single gradient metasurface” by Qi Liu, Xuan Liu, Yu Tian, Zhaohua Tian, Guixin Li, Xi-Feng Ren, Qihuang Gong and Ying Gu, 13 February 2025, Advanced Photonics Nexus. DOI: 10.1117/1.APN.4.2.026002
