Quantum computer memory using supercold atoms

09 June 2020

Interview with 

Lindsay LeBlanc, University of Alberta

COMPUTER_MEMORY

A hard drive, a thumb drive, and some SD cards.

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Chris Smith asked Bose-Einstein condensate researcher Lindsay LeBlanc, from the University of Alberta, about her research into quantum memory...

Lindsay - The advantages of using these quantum systems for quantum computing is that we are able to harness the unique properties of quantum mechanics to do different and maybe more powerful kinds of calculations using a quantum computer. And that's based on the fact of this quantumness, that there are these discrete energy levels in the atoms that we're working with. And so to start off with you don't necessarily need these atoms to be cold, but you do need them to be quantum. The nice thing about using these cold, condensed atoms to do this work is that, like I mentioned earlier, we eliminate randomness, and are able to control these atoms very carefully.

So we can take that information, which we encode in these different levels by having what we call superpositions - a little bit in the bottom and a little bit on the top - and then spread that across this whole quantum system, which is now, like I said earlier, bigger, macroscopic, easy to control. We can hold onto information and then retrieve it again at a later time. And the condensate makes that cleaner, the storage times can be longer, and we have better access to that information. And so that's one of the things that we're working on in my lab right now.

Chris - Would that mean then that if we did have a quantum computer, and it was going to exploit this physics, it would have to be working at really, really low temperature?

Lindsay - It would be, but only this small part would have to work at these low temperatures. You could think of it as one of the components inside of a PC tower computer. And there would be many different components working together. So this is just one small part of the computer, but one of the necessary parts for, say, memory to work.

Chris - We're talking about something, which it takes enormous lasers, a room full of lasers in order to make this. So can you shrink that down to something that's computer sized?

Lindsay - The hope is that yes. And in my lab, we're doing research. We don't focus on that, but there is actually a company in Colorado called ColdQuanta whose mission is to do exactly that. And I got an email from them just this week saying that a BEC was coming for everyone anytime now. So there are people who are working on that for sure.

Chris - And why will this be a step change for computing? If we do get a computer which works as a quantum computer, why is that any better than my Intel Pentium chip I have at the moment.

Lindsay - It's not necessarily better, but it's... I would say that it's different. It allows us to do different kinds of calculations, to do them more efficiently. There are certain things that quantum mechanics is very good at, and the kinds of algorithms that includes are searching and optimisation. And so it might allow a speed up for that. And then the other side of the coin is actually to do with security. So there are a number of proofs in quantum communications theory that say that information that is passed through quantum channels is unconditionally secure. And so you can have a new level of security that's not based on the random factorisation algorithms that are used at present.

Chris - The flip side of that of course, is as one person put it to me: if we do come up with a quantum computer, it'll be so good at considering all the options that every bit of security we've got in place will become instantly useless. Is that true?

Lindsay - Well that's right, but we need the quantum algorithms. So there's two parts to that. The quantum computer can break traditional security algorithms; but it can also provide a new pathway to a new kind of quantum security.

Chris - So how long before I can plug in my quantum computer and do Facebook on it at lightning speed?

Lindsay - I think it's decades before that happens, but these quantum communication channels to do security are actually they're any day now. And they are working in limited situations already. So that is here.

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