Advancements in Quantum Computing

The research published in the journal Science on September 18 marks a significant step towards building large-scale quantum computers, one of the most exciting scientific and technological challenges of the 21st century. Led by Dr. Holly Stump and her team at the University of New South Wales, the study reveals the potential to construct future chips for quantum computing using current technology and manufacturing processes.

Challenges in Quantum Computing

Quantum computing engineers face major challenges in balancing two opposing needs: protecting computing elements from external interference and noise, while also enabling them to interact for meaningful computations. As a result, various types of devices are still competing to be the first to operate a quantum computer.

Some devices excel in performing operations quickly but suffer from noise, while others are better at noise protection but difficult to operate and scale. The University of New South Wales team invested in a platform considered part of the latter category, using the nuclear spins of phosphorus atoms embedded in a silicon chip to encode quantum information.

Technical Innovations

The atomic nucleus is the cleanest and most isolated quantum element found in solid-state systems. Over the past 15 years, the University of New South Wales team has led breakthroughs that have made this technology a true contender in the quantum computing race. They have demonstrated the ability to retain quantum information for more than 30 seconds, an exceptionally long time in the quantum realm, and to perform quantum logic operations with less than 1% error.

Although the team achieved these feats in a silicon device, the isolation that keeps the atomic nuclei clean hinders communication in a large-scale quantum processor. Until now, operating the atomic nuclei required them to be very close together within a solid and surrounded by the same electron.

Quantum Communication via Electrons

The recent success marks an important step in improving communication between atomic nuclei. By using electrons as a communication medium, the team has enabled the atomic nuclei to interact over much greater distances than previously possible. In this way, electrons can “stretch” across space to interact with multiple atomic nuclei, allowing for the potential expansion of quantum devices.

In experiments, the distance between nuclei was about 20 nanometers, a very small distance but equivalent to the distance between Sydney and Boston if the nucleus were scaled to the size of a person.

Integration with Current Technology

Despite the unusual nature of the experiments, researchers affirm that these devices remain fundamentally compatible with the construction methods of all current computer chips. Phosphorus atoms were embedded in the chip by a team from the University of Melbourne, using an ultra-pure silicon wafer provided by Keio University in Japan.

By overcoming the need to link atomic nuclei with the same electron, the University of New South Wales team has removed the biggest obstacle to scaling silicon-based quantum computers reliant on atomic nuclei. More electrons could be used in the future to further extend the range of the nuclei.

Conclusion

This research represents a significant step in the development of quantum computing, as using electrons as a means of communication between atomic nuclei offers a way to overcome traditional challenges associated with isolation and noise. With compatibility with current manufacturing technologies, this advancement could contribute to building large-scale quantum computers, opening new horizons in technology and scientific research.