Experts respond to Google’s Willow quantum computing breakthrough

Dr Muhammed Esgin
Department of Software Systems & Cybersecurity, Faculty of Information Technology, Monash University

The recent announcement of Willow, Google’s new quantum computer chip, is good news for science and the development of large-scale quantum computers that may have wide-ranging benefits in the future. It is also another reminder of the fast-approaching quantum threat to cyber security mechanisms.

It is well-known in the research community that large-scale quantum computers can render today’s traditional encryption and cyber security mechanisms useless. These mechanisms are embedded in every part of our digitalised world from social media to securing critical infrastructure. The good news for now is that even Google’s Willow quantum computer is not nearly powerful enough to threaten today’s traditional cyber security protections … yet.

The US National Institute of Standards and Technology has finalised post-quantum encryption and digital signature algorithms, set to replace traditional encryption standards in the coming years. Transitioning to quantum-resistant cyber security is a complex process that will take years. Efforts like awareness campaigns and professional training, such as through events like our recent AusQRC 2024, are crucial to safeguarding our digital systems.

The Post-Quantum Cryptography in the Indo-Pacific Program at Monash University is an example of how we train IT professionals in various Indo-Pacific countries on how to identify quantum-vulnerable systems and develop a transition plan to move to quantum-resistant alternatives.

Our research on quantum-safe technologies is at the forefront of developing the foundations for cryptographic tools required to secure our digital systems. However, the number of experts is limited in Australia and more research investment in quantum-safe technologies is needed.

Karl Holmqvist
Founder and CEO of Lastwall

Google’s new processor, Willow, represents another step forward towards a quantum computational future. The ability to be “below threshold”, where scaling up and adding qubits reduces errors exponentially, is a notable advancement.

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In the last 24 months, we’ve seen significant milestones and breakthroughs across a variety of architectural approaches to building scalable quantum computers that are fault-tolerant.

It seems to me that we are significantly closer to a cryptographically relevant quantum computer than many people believe, and the rate of development is accelerating. However, I understand sceptics who think we might not be as close as it seems or that we may never build the capability to break current asymmetric cryptographic systems.

So, my question to everyone is this: Given that we will either deploy quantum-resilient solutions too early or too late, which scenario carries more risk?

Would you rather understand the implications of post-quantum cryptographic (PQC) deployments, test them in your environments, and be prepared to rapidly deploy when needed – or risk losing your secrets?

Bottom line: The time to understand, test, and deploy PQC capabilities is now. It works. Get moving.

Scott Aaronson
Schlumberger Centennial chair of Computer Science at the University of Texas at Austin

Yes, this is great. Yes, it’s a real milestone for the field. To be clear: for anyone who’s been following experimental quantum computing these past five years (say, since Google’s original quantum supremacy milestone in 2019), there’s no particular shock here. Since 2019, Google has roughly doubled the number of qubits on its chip and, more importantly, increased the qubits’ coherence time by a factor of five.

Meanwhile, their two-qubit gate fidelity is now roughly 99.7 per cent (for controlled-Z gates) or 99.85 per cent (for “iswap” gates), compared to ~99.5 per cent in 2019. They then did the more impressive demonstrations that predictably become possible with more and better qubits. And yet, even if the progress is broadly in line with what most of us expected, it’s still of course immensely gratifying to see everything actually work! Huge congratulations to everyone on the Google team for a well-deserved success.

Scientifically, the headline result is that, as they increase the size of their surface code, from 3×3 to 5×5 to 7×7, Google finds that their encoded logical qubit stays alive for longer rather than shorter. So, this is a very important threshold that’s now been crossed.

As Dave Bacon put it to me, “eddies are now forming” – or, to switch metaphors, after 30 years we’re now finally tickling the tail of the dragon of quantum fault-tolerance, the dragon that (once fully awoken) will let logical qubits be preserved and acted on for basically arbitrary amounts of time, allowing scalable quantum computation.

David Hollingworth

David Hollingworth has been writing about technology for over 20 years, and has worked for a range of print and online titles in his career. He is enjoying getting to grips with cyber security, especially when it lets him talk about Lego.