Dr Jorge Quintanilla talks about how physics can shape the future of transport and energy through superconductors and quantum computing.
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00:00Each Wednesday we'll be looking at the impactful research that affects
00:03our everyday lives here in Kent. Joining us on the line is Dr Jorge Quintanilla
00:09who is a reader in condensed matter theory. Jorge thank you so much for joining us this morning.
00:16Let's start with, there's a lot of big words there very early in the morning,
00:22let's start with what exactly is condensed matter theory?
00:26Hi Izzy, hi Cam, thanks for having me. Right, so probably most people haven't
00:33heard this expression before. Condensed matter theory is a branch of theoretical physics,
00:39so that's the branch of physics where we think about things and calculate rather than just do
00:44experiments, and it concerns the behavior of materials, or more generally what's a material
00:50for a physicist. A material is just a chunk of stuff that's made of trillions upon trillions
00:56of individual atoms, and we need to understand how all these atoms interacting together
01:02give rise to the properties we see, like some materials are magnetic, others are not magnetic,
01:08some are even have some more exotic properties, like they may be superconductors,
01:13and that's what we try to understand in close collaboration with the experimentalists who
01:19do the experimental materials, and we use all kinds of new techniques and technologies like
01:25AI or quantum computing, whatever we can use to understand these properties so we can predict them
01:32and perhaps come up with better materials that solve problems. Well that was going to be kind
01:37of leading on to my next question, which was you talk about that this is all a lot of theoretical
01:42and it's in that theoretical space, tell us some of those ways where it can be applied to
01:49real world situations, and how our viewers at home might see this theory be applied in the future.
01:59Absolutely, that's an excellent question. So what we have to understand is science is like a layered
02:05cake, there's many layers of the cake and the cherry on top, and the cherry on top is when
02:11something affects our everyday lives, but to get there to some improvement to our everyday lives,
02:17all the other layers have to be built first, right, if you are making a cake you don't start
02:22from the top and then slot the other bits underneath, you start with the base and then
02:27you put another layer and another layer, and basically different branches of theoretical
02:32physics are at different heights in this cake, and they are all important, even the most
02:38fundamental physics, like things that go on in particle accelerators where they're trying to
02:42understand the fundamental constituents of matter, you know, you cannot understand a material if you
02:47don't understand that it's made up of protons, neutrons and electrons, and so that's the general
02:53idea. So can I give you an example for instance? Absolutely, please. Great, so I mentioned
03:00superconductivity, that's a very strange property of some materials that when you cool them down a lot
03:06then they start behaving in different ways, and for example they may levitate in a magnetic field
03:13and float in midair and conduct electricity without any resistance, but you have to keep them very cold,
03:20and people have been investigating superconductors just because they are very interesting for a long
03:26time, but always, you know, we've been worried, well if you have to keep them very cold maybe they're not
03:31so useful, but actually you may have heard of this incredible revolution in computing going on now,
03:38which is quantum computing. Well quantum computing is based on computers that behave like according
03:45to the rules of quantum mechanics that usually apply only to very very small things you cannot
03:50see, like atoms, but a whole quantum computer, which you can see actually it takes a room, can behave
03:57in a way that is quantum, and this is made possible because these quantum processors, many of them
04:04are made of superconductor material. If we hadn't understood that a superconductor is basically a
04:10quantum object of the scale that you can see, then no one would have come up with that as a way to
04:16realizing quantum computers, and probably we still wouldn't have them, but this realization that
04:23superconductivity is a quantum phenomenon, it's something that theorists did in the 50s and the 70s,
04:31so that's why, you know, you need all the layers in the cake to get the cherry at the top.
04:36What can you do with a quantum computer? I'm so glad you asked because we are working on that at
04:44the University of Kent. There are many things you could do, so the important thing about a quantum
04:49computer is that it's not like a better computer, it's just a different computer. They work so
04:56differently to ordinary computers that some things that seemed impossible to ordinary computers
05:03are easy for quantum computers, and the other way around, some things that are easy you can
05:07do with your smartphone, a quantum computer couldn't do it, would be just too complicated.
05:11So one thing we're working at Kent, we're working on at Kent, is the following, is something called
05:17coordination problems. Imagine you have different people or different machines, they could be
05:22drones, they could be self-driving cars that need to coordinate their moves. For instance, two
05:27self-driving cars want to agree, well, you go that way, I go that way, so we don't collide, which is
05:33probably something you would want. Well, normally there are two options, either you are
05:41communicating, the two cars are sending signals to each other, or they agree a strategy and stick
05:47to it. If they just send signals to each other and all the cars in the future, maybe self-driving,
05:54and they are all exchanging signals, they're going to clog the airwaves. So that won't work,
05:59so they'll have to agree a strategy. And the problem with agreeing a strategy is maybe you say,
06:04well, I go this way, you go that way, but then the other car, when it's trying to go that way,
06:08it finds an obstacle that wasn't foreseen. And if there's no bandwidth to communicate,
06:12then you have a problem. Now, if the cars had on board little quantum computers, quantum memories,
06:20then they could store the strategy in that quantum memory in a way that when then something
06:24unexpected happens, the strategy can still change, even though the cars are not communicating,
06:31which seems a bit like magic. But that's exactly what we've researched recently, and we published
06:35a result recently, and we used an experimental quantum computer made available by IBM to actually
06:42use two qubits inside a quantum computer to simulate the two memories of the two cars,
06:47and see that we looked at a slightly different problem where they're trying to meet instead of
06:50avoid each other. We're also working on the collision avoidance problem. And then these
06:57two qubits, they simulated the two cars, and we showed that at least inside a quantum computer,
07:02this works. So it makes it more likely in this case that the two objects meet each other.
07:08So you see, we're all the time looking at new things you can do with quantum computers
07:12that are simply not possible with classical computers. And these are the most important
07:17technological revolutions are always not an improvement on what was before, but a completely
07:22new direction that opens things that you thought were impossible. And that's what quantum computing
07:27is about. Yeah, because I guess I've got the power and bandwidth to make something like that
07:32safe, and that's really exciting. And superconductors as well, they have the, because
07:38it's kind of like they keep their energy at low temperatures, right? So like your phone loses
07:44energy through heat, you know, and things like that, but they maintain it. So it could even maybe be
07:51the future of energy and transport and lots of different things, because it can maintain that
07:56kind of source without losing energy. Right, you're absolutely right. Another direction in
08:02superconductivity research is the fact they can conduct electricity without losses. And therefore,
08:08they can be very efficient for transporting energy. And of course, the difficulty is you have
08:12to keep them cold. That's why when you pass by the back of a hospital, there's often a very big
08:18bottle, the size of a house, a wide bottle that contains liquid helium, which is the rather
08:25expensive liquid you need to keep superconductors at low temperatures, because magnetic resonance
08:31imaging devices, MRIs, use superconductors. So that's another application of superconductors.
08:37In an MRI, you need a big magnetic field. To generate a big magnetic field, you need a current,
08:42an electrical current going in a loop. But if it's a very big current and your material is not
08:48superconducting, the material melts because of all the heat dissipated by the current.
08:54But if it's superconducting, then it's not offering resistance to the current. Therefore,
09:00there's no friction. Therefore, there's no heat. And as a result, you can achieve very large,
09:05very stable magnetic fields that allow you to see inside the human body. So sometimes it is
09:11worth going through all the trouble of cooling down the material to very low temperatures.
09:15But if we wanted to have power lines on the electrical grid that are all superconducting,
09:20it probably wouldn't be practical to keep them cold. So the search is on for room temperature
09:25superconductors. And that connects with what I was saying about condensed matter theory
09:30and trying to understand the fundamental properties of materials.