Global researchers gather in Waterloo for a conference on the quantum future

Many future game-changing technologies will be quantum. Scientists around the world are utilizing quantum information theory and the foundations of quantum mechanics to build practical quantum computers and other next-generation technologies.

For a country like Canada, participating in that “second quantum revolution” will necessarily involve national and global collaborations.

That effort recently received another boost: Year of Quantum Across Canada: From Fundamental Science to Applications, was a joint week-long conference hosted by Perimeter Institute and the Institute for Quantum Computing at the University of Waterloo. It brought together theorists and experimentalists from across Canada and beyond to discuss the latest advances in quantum information theory and how those advances can lead to applications.

Co-chaired by Marcela Carena, Executive Director of Perimeter Institute, and Norbert Lütkenhaus, Executive Director of the Institute for Quantum Computing (IQC) at the University of Waterloo, the conference included nearly 20 speakers from academic institutes across North America, Europe, and Asia, as well as industry representatives.

It was attended by more than 150 participants.

Carena and Lütkenhaus said the purpose was to bring together theorists and experimentalists on the academic side, as well as people from the private sector, to consider foundational questions surrounding quantum technology. The conference tackled issues such as: What will quantum computing technology be good for? What is the current state of the technology? What are the challenges ahead?

Their hope is that the conference, which had an organizing committee that included representatives from quantum information and technology ecosystems across Canada, will inspire new collaborations.

“We hope this will ignite new opportunities in the coming years,” Carena said. She and Lütkenhaus envision a future series of conferences, training initiatives, and collaborations between partner institutions that will keep the country at the forefront of quantum developments.

Lütkenhaus said quantum computing research has gone through something of a “phase transition” in Canada. Until now, a lot of effort has gone into developing quantum computing research ecosystems independently across the country, and Waterloo has been building a successful ecosystem over the last 25 years. But now, he said, there are opportunities for these ecosystems to work jointly and usher in a new phase: taking quantum research to the next level of applications.

“Historically, Perimeter and IQC have always been intertwined,” Lütkenhaus said. The two institutes were founded within a year of each other, thanks to donations from Canadian entrepreneur Mike Lazaridis, who was behind the BlackBerry smartphone. From the beginning, the two institutes have had faculty who are cross-appointed and joint graduate students and postdocs. But as the institutes evolve and new people come on board, it is important to strengthen those relationships, Lütkenhaus said. There is an opportunity to broaden the activities and to build new bridges with other quantum information ecosystems in Canada, he added.

The goal, said Carena and Lütkenhaus, is to make sure that Canada as a country — despite having a much smaller population compared to the United States — continues to punch well above its weight in quantum research that will lead to the next generation of innovations and technologies.

Carena said Canada has been a pioneer in quantum science, investing in it heavily and early when Perimeter and IQC were founded about 25 years ago. The two institutes have made many contributions, especially in areas like quantum key distribution and quantum algorithms, as well as advancing the quantum information theory that underlies it all.

But today, “it is a topic that is being pursued with a lot of energy and support in many other places in the world. We want to bring our collaborations closer together, so that we can help Canada remain competitive,” Carena said.

“I would say that the second quantum revolution is happening right now, so it is important to move strongly.”

How quantum information can reveal the secrets of nature

A keynote speaker at the conference was John Preskill, the Richard P. Feynman Professor of Theoretical Physics at the California Institute of Technology (Caltech). He provided an overview of the progress in quantum information science, the amazing opportunities ahead, and the challenges that remain.

In a recent paper, Preskill and his colleagues said, “the ultimate power of quantum technologies may emerge from advantages we cannot yet conceive.”

Quantum computing is just one application of quantum information theory, which is really all about how nature processes information. But it will also be important to other applications such as quantum sensing, quantum cryptography, quantum-secure communications networks, and quantum measurement (metrology). Some researchers are also applying it to theories that seek to explain quantum gravity — the attempt to bridge Albert Einstein’s general relativity (or theory of gravity), with quantum theory — something that can open a whole new window into the workings of nature.

In his talk at the conference, Preskill said when it comes to quantum computing, there are two central questions: “How are we going to scale up to quantum computing systems that can really solve our problems that are too hard to solve with conventional technology? And once we do so, what will be the most important applications to science and for industry?” The exploration of the “entanglement frontier” and the “complexity frontier” will be key to answering these questions, he said.

Instead of depending on just electrical signals that go through a computer gate or not, which generates the ones and zeros used for information processing in regular computing today, quantum computers use the quantum mechanical properties of particles like photons, electrons, trapped ions, and atoms to do the computing. One example  is the spin of the electron, in which the two levels can be taken as spin up and spin down. In a classical system, a bit would have to be in one state or the other. However, quantum mechanics allows for “qubits,” the basic units of quantum information, to be in superposition of both states simultaneously.

Preskill gave an analogy in his lecture: “You can think about it this way: Imagine a book which is 100 pages long. If it were a conventional book, you could read each of the 100 pages one at a time, and after you read all the pages, you know everything that's in the book. But suppose it's a quantum book. It's written in qubits and the pages are very highly entangled. When you look at a single page, you just see random gibberish, which tells you almost nothing about the content of the book. That's because in this quantum book, the information does not reside on the individual pages. It's encoded almost entirely in correlations. If you want to read the book, you need to make a collective observation of many pages at once.”

That's the essence of quantum entanglement, and it is different from correlations we're familiar with, Preskill said. “Part of the reason quantum entanglement is so interesting is its extravagant complexity.”

There is optimism that “eventually, with quantum computers, we'll be able to probe more deeply into the properties of complex molecules and novel materials, and also explore fundamental physics, say by simulating hydrogen collisions of elementary particles or the quantum properties of a black hole, or what was happening in the early universe right after the Big Bang,” Preskill said.

The evolution of quantum computing 

The late Richard Feynman was famously early in imagining quantum computing. “We can use, not just circuits, but some system involving the quantized energy levels, or the interactions of quantized spins,” he said, in his 1959 classic talk “Nanotechnology: There’s Plenty of Room at the Bottom” given at the annual meeting of the American Physical Society at Caltech. He was describing what are now known as qubits.

In the more than 60 years since then, quantum computing systems have been built and used to demonstrate "quantum advantage" (that is, getting them to solve problems that would be difficult to solve or take a prohibitively long time using even a supercomputer today).

But so far, those quantum computers have been used on very specific computational problems. There are big challenges ahead when it comes to scaling up these systems for real-world, commercial applications.

Preskill talked about the biggest problem: The “noise” in the system causes decoherence, where the qubits lose their quantum mechanical properties if there is any disruption from the outside environment (anything from disturbances in the earth’s magnetic field, to radiation from mobile phones, to influence of neighboring qubits). That noise will cause the quantum computations to collapse and generate errors. There are quantum error correction codes to protect the quantum information from the errors, but the more qubits there are, the harder it is to control the system.

Preskill said there is now a lot of interest now in using artificial intelligence (AI) to accelerate progress in quantum computing.

Many huge companies are involved in the next generation of quantum computing. Google Quantum AI and the IBM Quantum Platform are prime examples. But other, newer companies in North America and beyond are now also working on this. Canadian quantum computing company Xanadu is one of the companies that has been demonstrating quantum computational advantage. The conference included a panel discussion on Academia and Companies: What is their Role in Driving Innovation Forward?

In answering a question from the audience during his lecture, Preskill said despite the entry of many companies doing work in this field, he thinks it would be an error for governments and funding institutions to shift the flow of resources away from the academic world.

“I think that underestimates how far we have to go, to get to useful quantum utility quickly. I think we will need a lot more fundamental research. I don't agree at all with the idea that we understand enough about the science and now we can just use our engineering muscle to carry on,” Preskill said.

The future of quantum technology 

Other conference speakers and participants also expressed optimism about the future of quantum technologies while acknowledging that there are challenges on the road ahead.

One of the speakers at the conference was Martin Savage, a quantum information professor at the University of Washington who is working on applying quantum computing and information theory to fundamental physics. The “Grand Challenge” in that field is understanding the complex interactions and dynamics of matter. Quantum computers could be a huge benefit in untangling that complexity. 

Savage said in an interview that he believes the next 10 years will be “absolutely transformational” when it comes to what quantum computers will be capable of. “The technology is changing dramatically. If you look at what’s happened over the past five years, we’ve seen the emergence of multiple different quantum computing platforms. The calculations keep getting better and the size and type of calculations are getting bigger. We expect that progress to continue, going forward,” he said.  

There are significant challenges ahead in terms of controlling the qubits and preventing decoherence, but Savage said there is remarkable progress being made in those areas as well. 

If a practical quantum computer to solve real-world problems could be built, there are large potential payoffs in areas like materials science and chemistry, which will also have an impact on everything from clean energy to pharmaceuticals.

“We don't yet fully understand everything that quantum computers are going to do for us,” Savage said. But there are many applications where quantum computers might be able to offer at least some advantage in solving complex problems that are difficult or impossible to solve on computers today.

Christian Bauer from Lawrence Berkeley National Laboratory (LBNL) was a speaker at the conference plenary talk, Quantum Simulation for High Energy Physics. Originally from Germany, he did his PhD at the University of Toronto and is now head of the theory group at LBNL. He is working on how to use quantum computers to solve problems in particle physics.

In an interview, he made the analogy to the early days of classical computing. At first, in the 1970s, there were no computers that were remotely powerful enough to do much of anything in the everyday world. There were giant computers occupying entire rooms, used by NASA in space missions, but even they were primitive compared to the computer power of today. It took another 20 to 25 years —with a lot of theoretical work, along with advances in hardware — to reach the point where computers became ubiquitous.

We are in a similar situation with quantum computers today, Bauer said.

But despite the challenges ahead, Bauer said there is enormous potential for using quantum computers to better understand the Standard Model of particle physics and what lies beyond it.

“I think in the future, quantum computers will be able to simulate the dynamics of strong interactions (the complex and difficult to track interactions that happen between gluons and quarks in the nucleus of atoms). That’s the really big promise,” he said.

Some researchers, such as Christine Muschik, a faculty member at IQC and associate faculty at Perimeter, are exploring a whole new level of quantum computing — going beyond qubits and into the multi-level realm of qudits.

She worked with colleagues in an experimental group at the University of Innsbruck in Austria using qudits in a trapped ion quantum computer that manipulates calcium ions (charged calcium atoms).

Their paper, published in Nature Physics, “Simulating 2D lattice gauge theories on a qudit quantum computer”, explores the exciting potential of qudit quantum computers for understanding gauge theories -  the backbone of the Standard Model of particle physics.

At the conference, she discussed the latest developments using qudits. Muschik believes qudits have exciting potential in enabling quantum computers to do more with fewer quantum gates and thus reduce the errors. They could help make quantum computing more efficient, she said.

Muschik said conferences like this are important in bringing theorists and experimentalists together. In her own work, the collaborations have been essential.

“We now have this entire research stream using qudits,” Muschik said. The next step is the further development of the “toolbox” for qudit quantum computers, she added. “We can accumulate fewer errors using qudits, but the next step is to investigate when errors happen, how we can mitigate those errors and correct the errors on a qudit quantum computer.”

She envisions the possibility of “hybrid” quantum computers that can use both qubits and qudits. The qudit quantum computing, combined with qubits, “could give us added freedom,” she says.

Bauer said he gets many inquiries from young graduate students who are keenly interested in making the quantum future happen. Conferences like the one jointly put on by Perimeter and IQC are important in bringing people together and inspiring future research collaborations, he added.

Barry Sanders, who is the scientific director of the University of Calgary’s “Quantum City”, one of the Canadian ecosystems in the development of quantum technology solutions, was also a speaker at the conference. He is currently a visiting fellow at the Centre for International Governance Innovation located in Waterloo next door to Perimeter Institute, where he is researching policies to help guide the government in emerging dual-use technologies that can be used in a variety of civilian and military applications.

Sanders said that for Canada, research collaborations that are both national and global will be essential, not only to the development of future innovations, but also for multilateral governance on issues such as quantum security, technology investments, and markets. All of this will necessarily involve multiple countries working together to achieve common goals, he said.

A conference like the one between IQC and Perimeter is “one form of collision” that gets people talking and creates the synergies that might not happen otherwise, he added.  

Perimeter Institute Recorded Seminar Archive (PIRSA) is a free, searchable and citable archive of recorded seminars, conferences and lectures. Many of the lectures from the Year of Quantum Across Canada conference are available on the archive. The Institute for Quantum Computing also has a YouTube channel where lectures, interviews and educational materials about quantum computing are available for free.