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  • Translator: Morton Bast Reviewer: Thu-Huong Ha

  • The phenomenon you saw here for a brief moment

  • is called quantum levitation and quantum locking.

  • And the object that was levitating here

  • is called a superconductor.

  • Superconductivity is a quantum state of matter,

  • and it occurs only below a certain critical temperature.

  • Now, it's quite an old phenomenon;

  • it was discovered 100 years ago.

  • However, only recently,

  • due to several technological advancements,

  • we are now able to demonstrate to you

  • quantum levitation and quantum locking.

  • So, a superconductor is defined by two properties.

  • The first is zero electrical resistance,

  • and the second is the expulsion of a magnetic field from the interior of the superconductor.

  • That sounds complicated, right?

  • But what is electrical resistance?

  • So, electricity is the flow of electrons inside a material.

  • And these electrons, while flowing,

  • they collide with the atoms, and in these collisions

  • they lose a certain amount of energy.

  • And they dissipate this energy in the form of heat, and you know that effect.

  • However, inside a superconductor there are no collisions,

  • so there is no energy dissipation.

  • It's quite remarkable. Think about it.

  • In classical physics, there is always some friction, some energy loss.

  • But not here, because it is a quantum effect.

  • But that's not all, because superconductors don't like magnetic fields.

  • So a superconductor will try to expel magnetic field from the inside,

  • and it has the means to do that by circulating currents.

  • Now, the combination of both effects --

  • the expulsion of magnetic fields and zero electrical resistance --

  • is exactly a superconductor.

  • But the picture isn't always perfect, as we all know,

  • and sometimes strands of magnetic field remain inside the superconductor.

  • Now, under proper conditions, which we have here,

  • these strands of magnetic field can be trapped inside the superconductor.

  • And these strands of magnetic field inside the superconductor,

  • they come in discrete quantities.

  • Why? Because it is a quantum phenomenon. It's quantum physics.

  • And it turns out that they behave like quantum particles.

  • In this movie here, you can see how they flow one by one discretely.

  • This is strands of magnetic field. These are not particles,

  • but they behave like particles.

  • So, this is why we call this effect quantum levitation and quantum locking.

  • But what happens to the superconductor when we put it inside a magnetic field?

  • Well, first there are strands of magnetic field left inside,

  • but now the superconductor doesn't like them moving around,

  • because their movements dissipate energy,

  • which breaks the superconductivity state.

  • So what it actually does, it locks these strands,

  • which are called fluxons, and it locks these fluxons in place.

  • And by doing that, what it actually does is locking itself in place.

  • Why? Because any movement of the superconductor will change their place,

  • will change their configuration.

  • So we get quantum locking. And let me show you how this works.

  • I have here a superconductor, which I wrapped up so it'd stay cold long enough.

  • And when I place it on top of a regular magnet,

  • it just stays locked in midair.

  • (Applause)

  • Now, this is not just levitation. It's not just repulsion.

  • I can rearrange the fluxons, and it will be locked in this new configuration.

  • Like this, or move it slightly to the right or to the left.

  • So, this is quantum locking -- actually locking -- three-dimensional locking of the superconductor.

  • Of course, I can turn it upside down,

  • and it will remain locked.

  • Now, now that we understand that this so-called levitation is actually locking,

  • Yeah, we understand that.

  • You won't be surprised to hear that if I take this circular magnet,

  • in which the magnetic field is the same all around,

  • the superconductor will be able to freely rotate around the axis of the magnet.

  • Why? Because as long as it rotates, the locking is maintained.

  • You see? I can adjust and I can rotate the superconductor.

  • We have frictionless motion. It is still levitating, but can move freely all around.

  • So, we have quantum locking and we can levitate it on top of this magnet.

  • But how many fluxons, how many magnetic strands are there in a single disk like this?

  • Well, we can calculate it, and it turns out, quite a lot.

  • One hundred billion strands of magnetic field inside this three-inch disk.

  • But that's not the amazing part yet, because there is something I haven't told you yet.

  • And, yeah, the amazing part is that this superconductor that you see here

  • is only half a micron thick. It's extremely thin.

  • And this extremely thin layer is able to levitate more than 70,000 times its own weight.

  • It's a remarkable effect. It's very strong.

  • Now, I can extend this circular magnet,

  • and make whatever track I want.

  • For example, I can make a large circular rail here.

  • And when I place the superconducting disk on top of this rail,

  • it moves freely.

  • (Applause)

  • And again, that's not all. I can adjust its position like this, and rotate,

  • and it freely moves in this new position.

  • And I can even try a new thing; let's try it for the first time.

  • I can take this disk and put it here,

  • and while it stays here -- don't move --

  • I will try to rotate the track,

  • and hopefully, if I did it correctly,

  • it stays suspended.

  • (Applause)

  • You see, it's quantum locking, not levitation.

  • Now, while I'll let it circulate for a little more,

  • let me tell you a little bit about superconductors.

  • Now -- (Laughter) --

  • So we now know that we are able to transfer enormous amount of currents inside superconductors,

  • so we can use them to produce strong magnetic fields,

  • such as needed in MRI machines, particle accelerators and so on.

  • But we can also store energy using superconductors,

  • because we have no dissipation.

  • And we could also produce power cables, to transfer enormous amounts of current between power stations.

  • Imagine you could back up a single power station with a single superconducting cable.

  • But what is the future of quantum levitation and quantum locking?

  • Well, let me answer this simple question by giving you an example.

  • Imagine you would have a disk similar to the one I have here in my hand,

  • three-inch diameter, with a single difference.

  • The superconducting layer, instead of being half a micron thin,

  • being two millimeters thin, quite thin.

  • This two-millimeter-thin superconducting layer could hold 1,000 kilograms, a small car, in my hand.

  • Amazing. Thank you.

  • (Applause)

Translator: Morton Bast Reviewer: Thu-Huong Ha

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B2 TED superconductor quantum locking magnetic magnetic field

【TED】Boaz Almog "levitates" a superconductor

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    Shuishui posted on 2015/08/25
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