For a company that claimed more than three years ago that it had demonstrated “quantum advantage,” or the ability to achieve results on a quantum computer that would not be realistically achievable on a classical supercomputer, Google since then has been relatively quiet about its quantum efforts.
The company did open a dedicated quantum computing data center campus in Santa Barbara, California, in 2021, but updates on its achievements and ambitions in the quantum computing space otherwise have been few and far between. That relative radio silence is in clear contrast to the throng of quantum start-ups that over the last two to three years have been announcing funding, executive appointments, new products, and technology innovations on a daily basis.
Perhaps 2023 will be different, as none other than Google CEO Sundar Pichai this week touted Google’s latest quantum achievement, which he suggested is a major milestone in the field of error correction for quantum computers.
“For the first time ever, our Quantum AI researchers have experimentally demonstrated that it’s possible to reduce errors by increasing the number of qubits,” Pichai stated in a blog post. “In quantum computing, a qubit is a basic unit of quantum information that can take on richer states that extend beyond just 0 and 1. Our breakthrough represents a significant shift in how we operate quantum computers. Instead of working on the physical qubits on our quantum processor one by one, we are treating a group of them as one logical qubit. As a result, a logical qubit that we made from 49 physical qubits was able to outperform one we made from 17 qubits.”
This is significant because the race to build viable quantum computers so far largely has been a race for more and more qubits to increase the potential computing power of quantum machines. Yet, at the same time, there has been broad acknowledgement that error rates of today’s quantum computers are not sufficient for the use cases that already are developing for them.
For example, Subodh Kulkarni, a semiconductor industry veteran who recently became CEO of Rigetti Computing, has described error rates of up to 4% as alarmingly high. Speaking at an investor conference last month, he said, “I mean, any conventional computer system with 4% error rates would be a disaster. Nothing would work right.”
Pichai further explained in his blog post, “The challenge is that qubits are so sensitive that even stray light can cause calculation errors — and the problem worsens as quantum computers grow. This has significant consequences, since the best quantum algorithms that we know for running useful applications require the error rates of our qubits to be far lower than we have today. To bridge this gap, we will need quantum error correction.
Google is just one of many companies in the sector have been tackling the challenge by investing more time and money in the field of quantum error correction, but Google’s latest contribution to this field, outlined in Nature, seems promising because it demonstrates the “scaling of logical qubits” that are needed to improve accuracy, in part by increasing the size of quantum “surface code” used.
Pichai explained, “By encoding larger numbers of physical qubits on our quantum processor into one logical qubit, we hope to reduce the error rates to enable useful quantum algorithms.”