BRIAN GREENE: And are we going to read this?

BIRGITTA WHALEY: Yes, this was very important, because factoring large numbers lies at the heart of most of our encryption schemes–the encryption of your credit cards today, airline tickets, anything that you would think of.

And so, from that moment on, in a sense that sort of set the race to build such a quantum computer, and there’s been lots of advances experimentally then, over the last 20 years. And we’re now at the point where we have functioning devices with 9 or 10 quantum bits, the quantum analog of a classical bit.

And in the quantum bit, so as we saw those examples of the spinning electrons. So, classical bit will either be in a state 0 or 1, our digital universe, which we saw in outer space just now. But a quantum bit can be in a superposition–it can be any arbitrary superposition of 0 and 1, which means it will be both 1 or 0, or, and at the same time, 1 and 0. So it was just carrying this mystery along with us. And so we now have devices that are functioning with about 10 of these.

BRIAN GREENE: You say 10?

BIRGITTA WHALEY: Ten. Nine actually is the economical number right now. But people are working furiously now to build up to about 50, 60, and within a few years we should have somewhere close to 100.

And then once we get close to about 100, that’s a critical number because at that point, one starts to have real technical challenges in maintaining the quantum nature of the states of these machines. And that brings in these issues of the environment, decoherence, and also very, very delicate control.

And as Gerard mentioned, then you really have to know many, many many, many variables to really control every one of those variables, and that’s a really big both physics and engineering problem, which is just starting to be addressed now. And then after that, I think it’s impossible to predict how long it would take after that, if at all possible to go up to about 1000 or so, and 1000 is about the number where one would really have a machine which would do things that couldn’t be computed in the lifetime of a universe – on a classical machine. So that would be the real change for information processing.

BRIAN GREENE: Amazing. So we’re just about out of time, but I wanted to end on bringing this even further down to Earth, because you sort of sort out with the cosmos, black holes, wormholes, entanglement. There’s a wonderful demonstration in which these quantum mechanical ideas does something that I find eye-popping no matter how many times I’ve seen it.

Maybe some of you have seen it before – we have our fingers crossed. Omalon, can you come out one more time with our – with quantum levitation, if you would, which is a stunning demonstration of again, some of the strange ways in which quantum mechanics allows the world to work in ways that, again, a classical intuition would not expect.

And Omalon does this freehand. I’m going to stand back and – you want me to actually touch this? But I’m going to wear a glove. He only wears it to look like he’s being responsible – I see him do this bare hand all the time. You know, that’s just crazy, alright? That’s like 77 degrees or something? You know, Kelvin, which is cold.

OK, so let’s just go right to the disk if you would, and if you just put that there. And then I’m going to give this a little bit of a push around. Can you see that, up on the–? Can you get a shot of that? This is actually just hovering – can I give it a little bit more of a push? And what’s happening here, if you bring up the final slide that we have here, it’s called quantum locking.

It’s a wonderful application of quantum ideas that originated with some Israeli physicists who demonstrated this once before. You’ve got magnetic lines that are penetrating the superconducting disc. It’s cold–that allows it to be a superconductor. And the threads of these magnetic lines are able to, in some sense, able to pin this object along this track.

This track has uniform magnetic field, and as long as you keep it cold and superconducting, they will hold it in place. Here’s another illustration of these ideas. Look at that, can you get a close-up of that shot right there? Can you bring that up on the screen? There you go. So you see, that’s just hovering right there, and there’s nothing in between there.

And can we actually – can we flip this over and show how that goes? Yeah, so we can take this guy…and do you want…OK. And do you want a glove? No, you just want to do it by hand there. Yeah, OK. More fun that way, he says. OK, yeah. Wow, that’s insane. Now, can you get a shot of that underneath there? It is now hovering underneath, which is a fairly stunning and yes, right down to earth demonstration of quantum mechanics. Omalon, thank you. Totally cool. Appreciate that.

And I want to thank the entire panel for what I hope was an interesting journey. David Wallace, Birgitta Whaley, Mark Van Raamsdonk, and Gerard ‘t Hooft. So thank you very much. Thank you.

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