Chinese team achieves 16-dimensional quantum breakthrough over 50km fiber
A team of Chinese researchers has made a breakthrough in quantum communication by achieving stable 16-dimensional quantum key distribution over a 50km few-mode fibre link. The system maintained a low quantum bit error rate of just 1.2%, marking a significant step forward in secure data transmission. Their work also introduces a new chip-scale light source that could revolutionise photonic technologies in optical communications and quantum computing.
The research, led by Daoxin Dai, Jianji Dong, and colleagues from the National Key Laboratory of Solid-State Microwave Devices and Circuits and Nanjing Normal University, focused on developing a compact yet powerful multi-wavelength light source. Using an AlGaAs-on-insulator microresonator, the team generated eleven distinct wavelength pairs across a broad bandwidth. These correlated photon pairs demonstrated high spectral brightness, essential for efficient quantum information processing.
To ensure the integrity of high-dimensional quantum states, the researchers designed a novel mode demultiplexer with crosstalk below -20dB. This component preserved the fidelity of quantum signals, a critical requirement for reliable communication. The team also confirmed entanglement by violating the Clauser-Horne-Shimony-Holt (CHSH) Bell inequality, achieving a maximum S value of 2.810 ±0.028. The study further validated the generation of entangled photon pairs through coincidence histograms, which displayed the expected sinusoidal interference patterns. By combining a high-dimensional frequency encoding scheme with optimised fibre design, the researchers created a system capable of handling complex quantum states efficiently. Their findings suggest that fully integrated, deployable photonic systems with improved performance are now within reach.
This advancement enables more compact and powerful photonic devices, particularly in secure optical communications and quantum technologies. The successful demonstration of 16-dimensional quantum key distribution over 50km, along with the development of a chip-scale light source, confirms the feasibility of scalable, high-performance quantum systems. These innovations could soon lead to practical applications in next-generation secure networks and quantum computing infrastructure.
