18 Qubits: USTC Scientists Set New Quantum Entanglement Record


The new world record of 18-qubit quantum entanglement with six photons’ three degrees of freedom (6 × 3 = 18) has been achieved by USTC physicists PAN Jianwei (project leader), LU Chaoyang, LIU Naile, WANG Xilin et al., surpassing the previous world record of 10-qubit entanglement they made in 2016. The successful control over the high-dimensional entanglement is the key for speeding up quantum computing and the future quantum network.This breakthrough was published as the Editors’ Suggestion in the journal Physical Review Letters within only three weeks of submission.

Researchers developed high-stability interferometers for reversible quantum logic operations between the photons’ different degrees of freedom with precision and efficiencies close to unity, enabling simultaneous readout of 218 = 262,144 outcome combinations of the 18-qubit state. A state fidelity of 0.708 is measured, confirming the genuine entanglement of all 18 qubits.

Quantum computing has become a worldwide arena since its unlimited potential in the communication-related applications. The European Commission launched its “Quantum Technologies Flagship Final Report” with more than 1-billion-euro budget in 2016. The United States House Science Committee has introduced the 10-year National Quantum Initiative for the development of quantum technologies. Besides, tech giants such as Google, Microsoft and IBM have all been actively exploring the practical quantum applications.

Nevertheless, PAN’s team has been leading the field of quantum entanglement for the past two decades. In 2015, their work on the double quantum-teleportation was selected as the Physics World “Top Breakthrough of the Year”; in 2016, the team contributed to the development of the world’s first quantum satellite Micius, by which the satellite-to-ground level quantum entanglement was demonstrated; in 2017, PAN was named as Nature’s 10 with the label “Father of quantum”.

The work was supported by the National Natural Science Foundation of China, the Chinese Academy of Sciences, the National Fundamental Research Program and the Anhui Initiative in Quantum Information Technologies.


(Written by XU Yunfei, edited by HU Dongyin , USTC News Center)