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Raymond Laflamme and the potential of quantum computers

Raymond Laflamme switched from quantum cosmology to become a pioneer in the field of quantum information systems. (Photo: Institute for Quantum Computing, University of Waterloo)

AAASMC is going to Canada for the 2012 AAAS Annual Meeting held in Vancouver. We are using this as an opportunity to get to know some of our AAAS members who are from Canada.

Raymond Laflamme is the executive director of University of Waterloo's Institute for Quantum Computing and member of AAAS. He completed his Ph.D. on quantum cosmology under Stephen Hawking at the University of Cambridge and was partially responsible for convincing Hawking that time will not reverse in a contracting universe.

From 1991-2001 Laflamme worked at Los Alamos Research Laboratory, and his work on Nuclear Magnetic Resonance (NMR) was considered one of 1998's Ten Breakthroughs of the Year by Science. During this time his interest shifted from general relativity to quantum computing, developing theoretical approaches to quantum error correcting in the new field of quantum information theory.

Partially because of these error correcting codes, quantum computing systems have been shown to be, potentially, practically useful. Laflamme has conducted much of his work on NMR quantum computers, which uses the spin states of molecules as qubits or unites of quantum information.

Laflamme also holds a long-standing world record for the largest quantum computer at 12 qubits. To help make sense of quantum mechanics, Raymond Laflamme sat down with AAASMC to answer our questions.

AAAS MC: What about quantum science first grabbed your attention away from general relativity and what keeps you inspired today?
Raymond Laflamme, AAAS member and executive director of the Institute for Quantum Computing at the University of Waterloo: A conference in Santa Fe in 1994; I was working at Los Alamos National Laboratory at the time and I had the mentor Wojciech Zurek who told me that there was a very neat conference in Santa Fe related to the physics of information. He said ,"you should go because there are very neat people who are going," but I told him that I was not working in the physics of information and I was very busy. But he said, "you'll miss something." So I went, and at the conference there was this buzz, which you don't see very often at conferences, something important was going on. There was a person who gave a talk, his name was Umesh Vazirani from Berkeley and he's a very smart guy. He went in front of the audience and he said, \"I'm not going to talk about the work that I've done, I'm going to talk about someone else's work because I think it's pretty amazing." And it turned out it was work by Peter Shor who had shown that if we had quantum computers we would be able to efficiently factor numbers which are the product of primes and break codes. And you could see there was this buzz, there was just one idea circling around and everyone was talking about it.

I knew a little about quantum computing because I had a fellow at Los Alamos whose name was Seth Lloyd, who is now well known in the field. Seth and I loved to do back country expeditions and he'd always talk to me about quantum computing and I thought he was crazy. But with this presentation, I decided, this was very interesting.

I'd worked in a field called bicoherence, which is how quantum systems get, in some sense, corrupted from the interactions with their surroundings. So I came back from the conference trying to show that quantum computers will never work because of bicoherence. But I got scooped by someone I knew very well, a researcher in Vancouver who's name was Bill Unruh. And he pretty much had the same idea that I had. But Bill is somebody who likes to argue with people. If you tell him black, he will say white; if you tell him white, he will say black. So I used this technique and I said "he's proposing that quantum computers will not happen because of this, maybe he's wrong." And by doing this I kind of discovered or stumbled into what is called quantum error correction, a way of making quantum devices robust against noise. This was one thing that everyone in the community thought would be impossible to accomplish. So we now have an idea of how to make quantum devices robust in theory, but can we do this in practice? If we can make them robust, then they can become really practical devices. And I think these practical devices are going to change the technology in the 21st century.

AAAS MC: If you had to bet: on which technology will the first practical quantum computer be based, and what will non-physicists do with them?
Laflamme: That is the million-dollar question, but I'm going to give you a different answer than you probably expect. Most people who hear the word quantum computing think of a laptop that sits on the table in front of you, except there is a little switch on the side with a C for classic and a Q for quantum. And then you can switch it from one to another, and on the user experience there is no difference except things are going to happen much faster (when the switch is flipped to Q).

However, when we think about computers we are really thinking more than what is sitting in front of you. What you have in your car, the operation that controls how much air, fuel, and things like that, are going to the engine, those operations are, in some form, a computer. We have sensors more and more around us, which control temperature and things like that. Today they are automated. We program them, but we only program them once, we don't reprogram them for doing other things than what they've been built for. I'm going to put this as a family of computers. So there is the ideal, universal computer that is sitting in front of you, and there are others that do a multitude of things, they are pervasive in our society.

When your asking me what will be the first practical quantum computers, I will think of the later one and not the universal one. And they are starting to exist, computers based on spins of nuclei, electrons, atoms and photons. So we have small-scale quantum devices that are starting to become practical (which could potentially be used to  automate the systems around us).

But if you really put me against the wall there are three ideas that I think are really promising for the first universal quantum computers: either superconducting devices, ion traps or spin devices.

AAAS MC: To many of us on the fringes of cutting-edge science, it appears that a huge number of rather fundamental advances are currently being made, from remarkably delicate experiments to remarkable new insights on the very foundations of quantum theory.  Is there a common thread that ties together these wide-ranging advances?
Laflame: Very simple, what binds them together is that we are going deeper into the quantum world and learning how to control it. And we learn how to control it in many types of instances, or different types of technologies. Sometimes its photons, sometimes its ion traps, sometimes its NRM, but the thread between all of them is an increase and a more precise way of controlling the quantum world. Why is that important? Because if you look at the history of human kind and understanding the laws of physics, its a cycle that starts with curiosity, attempting to understand the laws, then attempting to control them, then finally attempting to turn them into technologies we can use in society. we've known quantum mechanics for nearly one hundred years now, but what we're learning is to control larger and larger quantum systems in a better and better way. This is what is opening the road for practical technology.

AAAS MC: You have chosen to do much of your experimental work in quantum computing on NMR systems. Why did you choose NMR?
Laflamme: I was trained not as an experimentalist but as a theoretician. So I did my Ph.D. at Cambridge on a field called Quantum Cosmology, a very theoretical field. And when I learned quantum information science, I stumbled onto this work on Quantum Error Correction and trying to make quantum systems robust. It was all theoretical. But I had this theory and I was wondering if the assumption of the theory were really the right assumptions for the physical world in which we live. So to understand this, I needed to go and look at experimental systems. I started to go and look in my community and it turns out that NMR has been around for many years and it is relatively easier to manipulate than the ion traps or the super connection qubits that I mentioned earlier. And I decided to make a jump and use that technology, which is slightly easier to use, to go and ask the questions and (NMR) answered them.

AAAS MC: If you care to be put on record, what do you think will be the next major advance in quantum information science?  How about in quantum physics as a whole? 
Laflamme: So we are just starting to make small devices, at a few quantum bits, where we can control them so we can predict what they are going to do, but they're still not very robust. So if I have one bit of quantum information I cannot keep it for very long. Although I mentioned to you this theory of holding quantum information using quantum errors systems, I think the real major advance will be the availability of keeping quantum information as long as we want on small devices. Not quantum computers yet, but the robust use of quantum systems.

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