TEDGlobal 2012
Boaz Almog: The levitating superconductor
Boaz Almog “懸浮”一個超導體
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為什麼一個非常薄，3 英寸厚的圓盤可以使其重量 70,000 倍的物體懸浮？在一個讓人目不轉睛，超現實的演示裡，Boaz Almog 向大家解釋，這個稱為量子鎖定的現象如何使一個超導體圓盤在磁鐵軌道上方懸浮--完全沒有摩擦力，也沒有能量損失。
Boaz Almog - Quantum Researcher
Boaz Almog uses quantum physics to levitate and trap objects in midair. Call it "quantum levitation." Full bio
Boaz Almog uses quantum physics to levitate and trap objects in midair. Call it "quantum levitation." Full bio
Double-click the English transcript below to play the video.
00:25
The phenomenon you saw here for a brief moment
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在這瞬間你看到的現象，
00:29
is called quantum levitation and quantum locking.
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稱作量子懸浮和量子鎖定。
00:36
And the object that was levitating here
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而這個懸浮中的物體
00:40
is called a superconductor.
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是超導體。
00:42
Superconductivity is a quantum state of matter,
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超導現象是物質的量子物理狀態，
00:47
and it occurs only below a certain critical temperature.
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它只會在低於特定的溫度時發生。
00:52
Now, it's quite an old phenomenon;
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其實超導體現象存在已久；
00:54
it was discovered 100 years ago.
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大約在一百年前就被發現了。
00:56
However, only recently,
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不過，
00:58
due to several technological advancements,
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依賴於最近的技術進步
(譯按:是說高溫超導體)
(譯按:是說高溫超導體)
01:00
we are now able to demonstrate to you
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我們才可以在此展示
01:03
quantum levitation and quantum locking.
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量子懸浮和量子鎖定。
01:07
So, a superconductor is defined by two properties.
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超導體具有兩種特徵。
01:12
The first is zero electrical resistance,
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其一是零電阻，
01:16
and the second is the expulsion of a magnetic field from the interior of the superconductor.
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其二是內部抗磁性。
01:23
That sounds complicated, right?
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聽起來很複雜,對嗎?
01:26
But what is electrical resistance?
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何謂電阻?
01:29
So, electricity is the flow of electrons inside a material.
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電力是電子在物質中流動,
01:35
And these electrons, while flowing,
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電子流動時會與原子碰撞，
01:38
they collide with the atoms, and in these collisions
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而這些碰撞
01:41
they lose a certain amount of energy.
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會使電子失去部份能量
01:43
And they dissipate this energy in the form of heat, and you know that effect.
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失去的能量會轉換成為熱，此謂之電阻
01:49
However, inside a superconductor there are no collisions,
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可是，在超導體中不會有此類碰撞，
01:55
so there is no energy dissipation.
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於是沒有能量流失。
01:59
It's quite remarkable. Think about it.
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這相當不平常。試想想。
02:02
In classical physics, there is always some friction, some energy loss.
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在古典物理學界，摩擦與能量流失無處不在。
02:07
But not here, because it is a quantum effect.
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但因為這是量子物理現象，所以不存在摩擦和能量損失。
02:11
But that's not all, because superconductors don't like magnetic fields.
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除此之外，因為超導體不喜歡磁場，
02:20
So a superconductor will try to expel magnetic field from the inside,
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超導體會通過使電流循環流動，
02:24
and it has the means to do that by circulating currents.
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而從其內部盡量把磁場排除。
02:31
Now, the combination of both effects --
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具備以上兩種特徵，
02:34
the expulsion of magnetic fields and zero electrical resistance --
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零電阻和內部抗磁性，
02:40
is exactly a superconductor.
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就是超導體。
02:43
But the picture isn't always perfect, as we all know,
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大家知道，事情並不總是完美的，
02:47
and sometimes strands of magnetic field remain inside the superconductor.
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有時候，一點點磁場會殘留在超導體內部。
02:54
Now, under proper conditions, which we have here,
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在適當的條件下，就如這裡可見，
02:58
these strands of magnetic field can be trapped inside the superconductor.
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這些殘留的磁場會被困在超導體裡。
03:03
And these strands of magnetic field inside the superconductor,
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而且這些殘留的磁場是離散量，
03:09
they come in discrete quantities.
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即不是連續的。
03:12
Why? Because it is a quantum phenomenon. It's quantum physics.
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為什麼？ 因為這是量子現象，量子物理。
03:16
And it turns out that they behave like quantum particles.
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它的行為就如量子一樣。
03:20
In this movie here, you can see how they flow one by one discretely.
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從影片可見，它一個個分開地移動。
03:25
This is strands of magnetic field. These are not particles,
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它是磁場，而非粒子，
03:29
but they behave like particles.
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但行為就如粒子一樣。
03:33
So, this is why we call this effect quantum levitation and quantum locking.
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這就是為什麼這個現象叫量子懸浮和量子鎖定。
03:38
But what happens to the superconductor when we put it inside a magnetic field?
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若將超導體置入一個磁場中會發生甚麼事呢?
03:44
Well, first there are strands of magnetic field left inside,
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嗯，首先是我們知道還有一些游離的磁場殘留在其中，
03:48
but now the superconductor doesn't like them moving around,
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但是超導體不會讓他們隨便移動
03:52
because their movements dissipate energy,
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因為移動就會有能量流失，
03:56
which breaks the superconductivity state.
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也就是說會破壞超導狀態。
03:59
So what it actually does, it locks these strands,
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所以超導體此時就會將這幾束所謂的磁通量子（磁場束）鎖定
04:03
which are called fluxons, and it locks these fluxons in place.
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將其固定在一個位置上
04:09
And by doing that, what it actually does is locking itself in place.
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如此一來，超導體自己也會被固定住。
04:15
Why? Because any movement of the superconductor will change their place,
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為什麼呢?因為超導體的任何移動
都會改變這些磁通量子的位置，
都會改變這些磁通量子的位置，
04:24
will change their configuration.
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也就改變了其格局。
04:26
So we get quantum locking. And let me show you how this works.
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這就是量子鎖定的由來。現在就讓我們來一探究竟，
04:31
I have here a superconductor, which I wrapped up so it'd stay cold long enough.
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現在我這裡有一個超導體，
事前已經用液氮包了起來，
這樣它可以保持在低溫的狀態足夠久。
事前已經用液氮包了起來，
這樣它可以保持在低溫的狀態足夠久。
04:37
And when I place it on top of a regular magnet,
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當我將它放置在一個一般的磁鐵上時，
04:42
it just stays locked in midair.
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它就這樣鎖定在半空中。
04:46
(Applause)
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(掌聲)
04:50
Now, this is not just levitation. It's not just repulsion.
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現在，這既不僅是懸浮，也不僅是排斥作用。
04:54
I can rearrange the fluxons, and it will be locked in this new configuration.
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我可以改變這些磁通量子的位置，它會被鎖定在新的格局裡。
04:59
Like this, or move it slightly to the right or to the left.
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就像這樣，或者是讓它偏左或偏右一點。
05:03
So, this is quantum locking -- actually locking -- three-dimensional locking of the superconductor.
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這就是量子鎖定--真正的鎖定--超導體的三維鎖定。
05:11
Of course, I can turn it upside down,
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當然，我也可以把這個鎖定的格局翻過來，
05:13
and it will remain locked.
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超導體仍然被鎖定在原來的位置。
05:16
Now, now that we understand that this so-called levitation is actually locking,
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現在我們已經知道所謂的懸浮其實是鎖定，
05:25
Yeah, we understand that.
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對，我們確實知道。
05:29
You won't be surprised to hear that if I take this circular magnet,
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不難想像，如果我用一個各面磁場都均一
05:33
in which the magnetic field is the same all around,
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的環狀磁鐵（來鎖定超導體），
05:37
the superconductor will be able to freely rotate around the axis of the magnet.
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超導體會圍繞着這個磁鐵的中軸自由旋轉。
05:43
Why? Because as long as it rotates, the locking is maintained.
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為什麼？因為只要超導體保持旋轉，
就可以維持鎖定的狀態。
就可以維持鎖定的狀態。
05:49
You see? I can adjust and I can rotate the superconductor.
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看到了嗎？我也可以調節，也可以轉超導體。
05:55
We have frictionless motion. It is still levitating, but can move freely all around.
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這是沒有磨擦力的運動。仍然是懸浮，
但是（超導體）可以自由地移動。
但是（超導體）可以自由地移動。
06:02
So, we have quantum locking and we can levitate it on top of this magnet.
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這就是量子鎖定，而我們可以讓超導體懸浮在磁鐵的上方。
06:11
But how many fluxons, how many magnetic strands are there in a single disk like this?
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不過，這樣一個圓盤到底有多少磁通量子，多少磁場條呢？
06:18
Well, we can calculate it, and it turns out, quite a lot.
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嗯，我們可以計算出來，結果是，非常多。
06:21
One hundred billion strands of magnetic field inside this three-inch disk.
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在這個3英寸直徑的圓盤裡，有100億條磁場。
06:28
But that's not the amazing part yet, because there is something I haven't told you yet.
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這還不是最驚人的部分，因為最驚人的我還沒告訴你。
06:32
And, yeah, the amazing part is that this superconductor that you see here
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最驚人的是，這個你現在看到的超導體，
06:38
is only half a micron thick. It's extremely thin.
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只有一微米厚，非常地薄。
06:45
And this extremely thin layer is able to levitate more than 70,000 times its own weight.
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而這個超薄的超導體可以
懸浮起其自身重量70,000倍的物體。
懸浮起其自身重量70,000倍的物體。
06:55
It's a remarkable effect. It's very strong.
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這是非常不尋常的事。它非常強壯。
07:01
Now, I can extend this circular magnet,
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接下來，我把這個環形的磁鐵延伸，
07:04
and make whatever track I want.
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把它做成任何我想要的軌道。
07:09
For example, I can make a large circular rail here.
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比如說，我可以做一個像這樣的大圓環軌道。
07:13
And when I place the superconducting disk on top of this rail,
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然後，當我把這個超導體圓盤放到軌道上方時，
07:20
it moves freely.
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它會自由地（沿著軌道）移動。
07:24
(Applause)
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（掌聲）
07:33
And again, that's not all. I can adjust its position like this, and rotate,
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而且，除此之外，我還可以調節它的位置，像這樣，然後旋轉，
07:38
and it freely moves in this new position.
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它仍會在其新的位置上自由移動。
07:45
And I can even try a new thing; let's try it for the first time.
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我甚至可以試試我還沒有試過的變化；
07:49
I can take this disk and put it here,
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我可以把這個超導體放在這裡，
07:55
and while it stays here -- don't move --
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在它鎖定後--別動--
07:58
I will try to rotate the track,
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我要試著把這個磁鐵軌道翻過來，
08:04
and hopefully, if I did it correctly,
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希望，如果我沒錯的話，
08:07
it stays suspended.
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它會仍然懸浮。
08:09
(Applause)
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（掌聲）
08:18
You see, it's quantum locking, not levitation.
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各位，這就是量子鎖定，不是懸浮。
08:25
Now, while I'll let it circulate for a little more,
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接下來，在它繼續轉的時候，
08:29
let me tell you a little bit about superconductors.
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我要再告訴你一些關於超導體的其他事情。
08:33
Now -- (Laughter) --
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現在--（笑聲）--
08:39
So we now know that we are able to transfer enormous amount of currents inside superconductors,
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我們現在知道我們可以在超導體內傳導巨大的電流，
08:46
so we can use them to produce strong magnetic fields,
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我們可以用超導體來產生強大的磁場，
08:51
such as needed in MRI machines, particle accelerators and so on.
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如磁共振成像儀，粒子加速器等所需的巨大磁場。
08:56
But we can also store energy using superconductors,
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我們也可以用超導體儲存能量，
09:01
because we have no dissipation.
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因為沒有能量耗散。
09:02
And we could also produce power cables, to transfer enormous amounts of current between power stations.
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我們也可以用超導體製造電纜，在電站間運送電流。
09:10
Imagine you could back up a single power station with a single superconducting cable.
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想像一下，你可以用一根超導電纜來給一整個電站供電。
09:19
But what is the future of quantum levitation and quantum locking?
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那麼，量子懸浮和量子鎖定的未來是什麼？
09:23
Well, let me answer this simple question by giving you an example.
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嗯，讓我舉個例子來回答這個簡單的問題。
09:30
Imagine you would have a disk similar to the one I have here in my hand,
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想像你有像我這樣的一個圓盤在手裡，
09:37
three-inch diameter, with a single difference.
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3英寸直徑，唯一不同的是，
09:41
The superconducting layer, instead of being half a micron thin,
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這個超導片不是一微米厚，
09:46
being two millimeters thin, quite thin.
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而是兩毫米厚，仍然很薄。
09:49
This two-millimeter-thin superconducting layer could hold 1,000 kilograms, a small car, in my hand.
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這個兩毫米厚的超導片可以
在我手裡舉起1000公斤，一輛小車。
在我手裡舉起1000公斤，一輛小車。
10:00
Amazing. Thank you.
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很驚人吧。謝謝
10:03
(Applause)
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（掌聲）
ABOUT THE SPEAKER
Boaz Almog - Quantum ResearcherBoaz Almog uses quantum physics to levitate and trap objects in midair. Call it "quantum levitation."
Why you should listen
In October 2011, Boaz Almog demonstrated how a superconducting disk can be trapped in a surrounding magnetic field to levitate above it, a phenomenon called “quantum levitation.” This demonstration, seemingly taken from a sci-fi movie, is the result of many years of R&D on high-quality superconductors. By using exceptional superconductors cooled in liquid nitrogen, Almog and his colleague Mishael Azoulay at the superconductivity group at Tel Aviv University (lead by Prof. Guy Deutscher) were able to demonstrate a quantum effect that, although well known to physicists worldwide, had never been seen and demonstrated in such a compelling way.
Experiment credits:
Prof. Guy Deutscher, Mishael Azoulay and Boaz Almog
High Tc Superconductivity Group
School of Physics and Astronomy
Tel Aviv University
Watch more footage from this demo >>
Boaz Almog | Speaker | TED.com