Lawrence Krauss Explains Quantum Computing

 Quantum Computers  

In a new video from Big Think, physicist and author Lawrence Krauss describes quantum computing and the technical obstacles we need to overcome to realize this ambitious technological goal.

In the video above from Big Think, Lawrence Krauss describes quantum computing and the technical obstacles we need to overcome to realize this Holy Grail of processing.

According to Krauss, author of A Universe from Nothing, the difference between a quantum computer and a regular computer, is at some level. In a regular computer, you've got ones and zeros, which you store in binary form and you manipulate them and they do calculations.

In the quantum world, explains Krausss, particles like electrons are actually spinning in all directions at the same time, one of the weird aspects of quantum mechanics. We may measure, by doing a measurement of an electron, find it's spinning this way. But before we did the measurement, it was spinning this way and this way and that way and that way all at the same time.

This means, if the electron's spinning in many different directions at the same time, if we don't actually measure it, it can be doing many computations at the same time. "And so a quantum computer is based on manipulating the state of particles like electrons so that during the calculation, many different calculations are being performed at the same time, and only making a measurement at the end of the computation."

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If we could exploit that fact of quantum mechanics that particles could do many things at the same time, we would be able to do many computations at same time. And that's what would make a quantum computer so powerful.

"One of the reasons it's so difficult to make a quantum computer, and one of the reasons I'm a little skeptical at the moment, is that - the reason the quantum world seems so strange to us is that we don't behave quantum mechanically. I don't -- you know, you can - not me, but you could run towards the wall behind us from now 'til the end of the universe and bang your head in to it and you'd just get a tremendous headache," states Krauss. "But if you're an electron, there's a probability if I throw it towards the wall that it will disappear and appear on the other side due to something called quantum tunneling, okay."

Krauss is therefore in the camp that says the D-Wave system is not, in fact, a quantum computer. This despite the rising support that the Burnaby B.C.-based company's product is the real thing.  

Krauss maintains that the problem with a quantum computer is essentially quantum behavior.

"You want to make this macroscopic object, you want to keep it behaving quantum mechanically which means isolating it very carefully from, within itself, all the interactions and the outside world. And that's the hard part, Is isolating things enough to maintain this what's called quantum coherence. And that's the challenge and it's a huge challenge."

The potential of quantum computers is unbelievably great. Once you can engineer materials on a scale where quantum mechanical properties are important, a whole new world of phenomenon opens up.

Krauss says, "You might be able to say - as we say, if we created a quantum computer, and I'm not - I must admit I'm skeptical that we'll be able to do that in the near-term, but if we could, we'd be able to do computations in a finite time that would take longer than the age of the universe right now. We'd be able to do strange and wonderful things. And of course, if you ask me what's the next big breakthrough, I'll tell you what I always tell people, which is if I knew, I'd be doing it right now."


SOURCE  Big Think

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