China Reaches 98% Efficiency With a Single Quantum Router on Origin Wukong

Chinese scientists have tested a quantum router on the Origin Wukong superconducting quantum computer, reaching a transmission efficiency of up to 98%. The experiment is a step toward building scalable quantum random-access memory, or QRAM, Interesting Engineering reports.

The work targets the bucket-brigade QRAM architecture, where dedicated quantum routers direct information to specific memory cells. As memory size grows, so does the number of routers needed. That makes preserving a quantum state across multiple network layers one of the biggest technical hurdles.

The team built three independent quantum routers and then combined them into a two-layer network. This let them test the technology both as a single component and in a more complex setup.

A single router reached a transmission efficiency of 98%. Once the devices were combined into the two-layer system, that figure dropped to 93%. In random-access tests, quantum state fidelity reached 94.8% for a single router and 82.4% for the two-layer network.

The 98% figure isn’t a measure of the whole quantum computer’s accuracy, or of QRAM as a system — it reflects the performance of one experimental router. The drop as more layers are added shows the challenges researchers will face when scaling up the architecture.

The tests ran on Origin Wukong, a third-generation Chinese superconducting quantum computer. According to the researchers, the approach could eventually help build larger quantum memory systems on existing superconducting hardware, and support tighter integration between quantum chips and control electronics.

For now, this is only an experimental demonstration of quantum routing, not a working large-scale QRAM. The next step is adding more routers and network layers while keeping transmission efficiency and state fidelity high.

The result adds to a string of recent tests of quantum-networking hardware by different teams worldwide, from fiber-optic quantum links to satellite-based quantum communication trials.