What did researchers from Origin Quantum, the University of Science and Technology of China, and their partners report in Physical Review X in early September 2026 about coherent bucket-style quantum random-access memory routing on China’s third-generation superconducting Origin

The teams reported an experimental, coherent bucket-brigade QRAM routing primitive on Origin Wukong: address-controlled routing of quantum information through a real superconducting chip, rather than a complete, deployable QRAM memory. The result is significant as a measured demonstration of reversible quantum data movement on domestic hardware, but it does not establish near-term commercial QRAM. 147

What was demonstrated

• A single router reportedly reached up to about 98% information-transmission efficiency; reporting around the work gives an average single-router fidelity of about 94.8% (the accessible preprint abstract instead states an individual-router maximum fidelity of 95.74%). 41

• Three independently implemented routers were connected into a two-layer network. In random-access tests, the network reportedly achieved roughly 93% transmission efficiency and 82.4% average routing fidelity. 71

• The architecture is a bucket-brigade QRAM design: a binary tree of routers directs information according to an address, rather than requiring every memory route to be explicitly activated. 12

How the routing scheme works

• The router uses a transition-composite-gate approach: auxiliary higher energy levels of superconducting devices temporarily mediate conditional interactions, driven by microwave control pulses. This reduces circuit depth relative to decomposing the operation into many ordinary digital gates. 1

• Address information is encoded in non-adjacent qutrit states, |0⟩ and |2⟩. That choice supports “eraser detection”: post-selection can discard events indicating certain control errors or leakage, providing some error filtering without the extensive dedicated qubit overhead of full quantum error correction. 1

• The intended benefit is that routing remains coherent and reversible—an address can steer quantum data while preserving superposition—while avoiding deep gate sequences whose accumulating errors and decoherence become more severe as a routing tree grows. 1

Why the result matters—and what it does not show

• It is credible evidence that coherent, address-controlled routing can be assembled and measured on a physical superconducting processor, including a cascaded two-layer network rather than only a simulated or isolated component. 17

• The headline 98% is a single-router transmission metric, not proof of fault-tolerant QRAM performance at useful memory scale; the two-layer fidelity falling to 82.4% illustrates the compounding challenge. 71

• Important unresolved engineering barriers include microwave-control crosstalk, stable operation at cryogenic temperatures, wiring/control and integration cost, calibration complexity, and maintaining fidelity when extending from two layers to four or eight layers. The available evidence does not establish that those scale-up problems have been solved. 12

• One publication detail needs caution: the accessible primary record is an arXiv preprint dated August 24, 2026 and labeled “Preprint: APS/123-QED”; the supplied evidence does not independently confirm a final Physical Review X article, volume, or DOI. 1