Physicists linked 13 photonic qubits into genuine entanglement without destroying a single photon. This took place in the laboratory of Tsinghua University in China, where a team led by Hongyi Zhang applied quantum non-demolition measurement and deterministic fusion of graph states.
The researchers first created small entangled groups of microwave photons using superconducting circuits. The information was encoded in different time slots of the photons. Then a quantum non-demolition detector measured selected pairs, projecting them into a Bell state, and joined the smaller graph states into a single whole. Frequency tuning made it possible to choose which pairs took part in the fusion, making the process programmable. Active reset and reuse of the superconducting qubits, together with error correction, reduced the influence of decoherence.
As a result, it proved possible to achieve genuine multipartite entanglement of 13 photonic qubits at once. This means that the entanglement spanned the entire group as a whole, rather than being limited to individual subgroups. The quantum non-demolition measurement here works like checking the weight of a closed book: the information is extracted, while the object itself remains untouched and ready for further use.
Such a scheme opens the way to scalable photonic quantum networks. Large graph states become a resource for measurement-based computing, quantum communication and error-correction schemes. Unlike probabilistic methods of linear optics, the new approach is deterministic and does not require repeated attempts.
The results were published in the journal Nature Physics on 10 October 2026. The team is already planning to build architectures with multiple detectors for even larger and more complex states.
This is a real experiment in which every photon retained its quantum nature and continued to participate in the overall entangled network.
