NextFin news, On Friday, September 19, 2025, a team of quantum engineers at the University of New South Wales (UNSW) in Sydney announced a significant breakthrough in quantum computing by successfully entangling two atomic nuclei implanted in silicon chips at a distance of about 20 nanometres. The entanglement was achieved by using electrons as quantum mediators, enabling the distant nuclei to communicate quantum information despite their physical separation.
The research, published in the journal Science, was led by Dr. Holly Stemp and Scientia Professor Andrea Morello from UNSW's School of Electrical Engineering and Telecommunications. The team used phosphorus atoms implanted in ultra-pure silicon, encoding quantum information in the nuclear spins of these atoms. Electrons, which can spatially spread and interact with multiple nuclei, acted as 'telephones' to link the distant atomic nuclei, allowing them to become quantum entangled.
Quantum entanglement is a fundamental phenomenon where particles become interconnected such that the state of one instantly influences the state of another, regardless of distance. This property is essential for quantum computers to perform computations beyond the capabilities of classical computers. However, achieving entanglement between well-isolated quantum bits (qubits) like atomic nuclei, which are highly resistant to noise but difficult to couple over distance, has been a major challenge.
Previously, entanglement of nuclear spins in silicon required the nuclei to be extremely close, sharing the same electron. The UNSW team's method overcomes this limitation by enabling entanglement between nuclei separated by 20 nanometres—roughly the scale of modern silicon transistors—using electron exchange interactions. This distance corresponds to fewer than 40 silicon atoms between the phosphorus atoms, demonstrating compatibility with existing semiconductor fabrication processes.
Dr. Stemp explained that this breakthrough is akin to giving isolated nuclei 'telephones' to communicate across separate 'rooms,' allowing scalable quantum interactions without sacrificing the nuclei's isolation from noise. Professor Morello emphasized that electrons can be manipulated and shaped to extend the entanglement range further, providing a practical path toward large-scale quantum processors based on nuclear spin qubits.
The phosphorus atoms were implanted by a team at the University of Melbourne, and the silicon substrate was supplied by Keio University in Japan, highlighting international collaboration. The UNSW researchers noted that their approach balances the need for qubit isolation to preserve coherence with the ability to perform controlled interactions necessary for quantum logic operations.
This advance represents a key step toward integrating long-lived, well-shielded nuclear spin qubits into silicon-based quantum chips, leveraging the trillion-dollar semiconductor industry's manufacturing infrastructure. It opens the door to scalable quantum computing architectures that combine the stability of nuclear spins with the flexibility of electron-mediated coupling.
The research received funding from the Australian Research Council, the Australian Department of Defence, and the US Army Research Office. The full study is accessible via Science journal.
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