Xanadu Quantum Technologies, one of several companies trying to harness the ephemeral nature of quantum physics to revolutionize the computer industry, has hit an elusive milestone with a device that can outperform any supercomputer in the world at a specific task.
In a paper published Wednesday in the research journal Nature, the Canadian company described how its machine, a quantum computer dubbed Borealis, achieved “quantum advantage” – a term that means it delivered a result beyond the practical reach of a conventional computer system.
Specifically, Borealis provided a series of numbers with a specified range of probability in just 36 millionths of a second, an operation that would take the world’s most powerful supercomputers more than 9,000 years to match. The feat does not have immediate application, but scientists at Xanadu had to surmount several key challenges to accomplish it.
“That’s what we think is really great about this,” said Christian Weedbrook, Xanadu’s founder and chief executive officer, during an interview at the company’s headquarters, where Borealis sits on the 29th floor of an office building overlooking downtown Toronto. “A lot of those breakthroughs are what we need in order to get to a quantum computer that is useful to customers.”
He said that the achievement “plants the flag for Canada” in the race to develop what is known as a universal quantum computer – a system that can, in future, be use to topple computational barriers in areas as diverse as cybersecurity, drug discovery, materials science, financial risk modelling and climate change mitigation.
The company has also invited outside users – from expert researchers to the merely curious – to test out Borealis over the internet.
As with previous cases in which quantum advantage has been demonstrated, a clever use of conventional computers may emerge that can mimic the quantum system – a tactic known in the field as spoofing.
Even so, said Barry Sanders, director of the Institute for Quantum Science and Technology at the University of Calgary, what matters more about what Xanadu has done is that it reinforces the view that the industry is on a path toward universal quantum computing.
“It’s not a minor step, it’s a big leap forward,” said Dr. Sanders, who is not affiliated with Xanadu.
To the novice eye, Borealis looks more like a science experiment than a computer. It is composed of optical fibres, mirrors and other light-guiding components spread out on a tabletop, with supporting electronics on shelves above. Its operating elements are pulses of squeezed light – infrared laser light that has been manipulated to exhibit certain quantum properties.
As the pulses travel through the system, some are sent on long looping paths that, at three points, allow them to double back and interact with pulses following behind. These increasingly entangled pulses act as the system’s qubits – analogous to the 1s and 0s in a conventional computer, but more versatile because quantum weirdness allows them to hold a mixture of values that collectively solve the task.
The approach, known as photonics, has the advantage of being able to operate at room temperature. One disadvantage is that some light is inevitably lost as it travels through the optical hardware. But other types of quantum computers come with their own trade-offs.
The first system to demonstrate quantum advantage, unveiled by Google in 2019, used cryogenically cooled superconducting circuits as qubits. One year later, researchers at the University of Science and Technology of China claimed quantum advantage with a light-based system. Neither crossed the 100-qubit threshold.
In contrast, Borealis is a 216-qubit device with features that its designers say will allow them to scale up more easily. (Another Canadian company, D-Wave Systems Inc., has reached the level of thousands of qubits with a non-universal form of quantum computing that is applicable to a narrower class of problems.)
Experts estimate it will take at least one million qubits to make a quantum computer that is commercially relevant. This is because most of those qubits will be needed to correct errors that creep into any quantum system. Like the earlier systems that showed quantum advantage, Borealis does not include error correction in its design, a hurdle the field has yet to clear.
Jonathan Lavoie, who led the development of Borealis for Xanadu, said the system was conceived and assembled during the height of the COVID-19 pandemic, with team members working together online to hammer out the details of its operation.
Its debut comes as the company is in the midst of raising US$100-million, led by Toronto growth equity firm Georgian, in a deal valuing Xanadu at US$1-billion, The Globe reported last month. Other Xanadu investors include U.S. funds Bessemer Venture Partners and Tiger Global Management LLC, Canadian billionaire Jeff Skoll, American venture capitalist Tim Draper, BDC Capital and the U.S. Central Intelligence Agency’s In-Q-Tel venture capital arm.
Margaret Wu, a lead investor with Georgian, said Xanadu “has been incredibly capital efficient” and made greater advances after raising and spending less money than quantum computing rivals. She said Xanadu has continued to exceed internal expectations and “they are further along than we had expected when we originally invested, and they did it while conserving cash” during the pandemic.
“It’s remarkable they’ve been able to stay on track and continue staying ahead of a lot of the other approaches out there,” Ms. Wu said.
As quantum technology has advanced, so has investor interest, even though the industry is still far from delivering a commercially relevant device. Research firm Gartner has predicted that nearly 40 per cent of large enterprises will pursue quantum initiatives by 2025.
“This is the commercialization of a branch of physics that’s going to completely redefine everything eventually, but it’s going to take time,” said Stephanie Simmons, founder and chief quantum officer at Coquitlam, B.C.-based quantum technology company Photonic Inc.
For now, the industry is in what Gartner analyst Chirag Dekate has described as an embryonic state at best.
Several quantum computer developers, Xanadu among them, have customers and research partners that include corporate giants such as Volkswagen AG and Amazon.com Inc., but most of the work those developers do is experimental and exploratory.
“The technology is not at the point that you have a concrete business value, concrete practical implication,” said Dr. Arne-Christian Voigt, head of the breakthrough technologies and innovation group with Volkswagen, which has performed research projects using quantum machines from Xanadu, D-Wave Systems, Google and IonQ Inc.
Dr. Voigt called Xanadu’s achievement “a very significant step for photonic quantum computing,” but he said “it’s an open question” whether any quantum computer can live up to the hype. “At the moment it is open which kind of technology will make the run later on.”
IVAN SEMENIUK, SCIENCE REPORTER
SEAN SILCOFF, TECHNOLOGY REPORTER
The Globe and Mail, June 1, 2022