Boaz Almog "levitates" a superconductor

773,189 views ・ 2012-07-02

TED


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00:00
Translator: Morton Bast Reviewer: Thu-Huong Ha
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譯者: Yukun Chen 審譯者: 盧 曉天
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。
00:35
And the object that was levitating here
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而這個懸浮中的物體
00:39
is called a superconductor.
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是超導體。
00:41
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。
00:51
Now, it's quite an old phenomenon;
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其實超導體現象存在已久;
00:53
it was discovered 100 years ago.
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大約在一百年前就被發現了。
00:55
However, only recently,
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不過,
00:57
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)
01:00
we are now able to demonstrate to you
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我們才可以在此展示
01:02
quantum levitation and quantum locking.
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量子懸浮和量子鎖定。
01:06
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,
01:15
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。
01:22
That sounds complicated, right?
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聽起來很複雜,對嗎?
01:25
But what is electrical resistance?
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何謂電阻?
01:28
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,
01:34
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
01:40
they lose a certain amount of energy.
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會使電子失去部份能量
01:42
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
01:48
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,
01:54
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,
02:19
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。
02:30
Now, the combination of both effects --
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具備以上兩種特徵,
02:33
the expulsion of magnetic fields and zero electrical resistance --
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零電阻和內部抗磁性,
02:39
is exactly a superconductor.
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就是超導體。
02:42
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,
02:46
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,
02:57
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。
03:02
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。
03:15
And it turns out that they behave like quantum particles.
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它的行為就如量子一樣。
03:19
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,
03:28
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。
03:37
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?
03:43
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,
03:55
which breaks the superconductivity state.
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也就是說會破壞超導狀態。
03:58
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
04:02
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
04:08
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,
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。
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,
04:41
it just stays locked in midair.
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它就這樣鎖定在半空中。
04:45
(Applause)
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(掌聲)
04:49
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。
04:53
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。
04:58
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。
05:02
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。
05:10
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,
05:12
and it will remain locked.
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超導體仍然被鎖定在原來的位置。
05:15
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,
05:24
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。
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。
06:01
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?
06:17
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。
06:20
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。
06:27
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,
06:37
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。
06:54
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。
07:00
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。
07:08
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。
07:12
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,
07:19
it moves freely.
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它會自由地(沿著軌道)移動。
07:23
(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,
07:37
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。
07:44
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;
07:48
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,
07:54
and while it stays here -- don't move --
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在它鎖定後--別動--
07:57
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,
08:06
it stays suspended.
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它會仍然懸浮。
08:08
(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。
08:32
Now -- (Laughter) --
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現在--(笑聲)--
08:38
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,
08:45
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,
08:50
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。
08:55
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,
09:00
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。
09:09
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。
09:18
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,
09:36
three-inch diameter, with a single difference.
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3英寸直徑,唯一不同的是,
09:40
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,
09:45
being two millimeters thin, quite thin.
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而是兩毫米厚,仍然很薄。
09:48
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。
09:59
Amazing. Thank you.
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很驚人吧。謝謝
10:02
(Applause)
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(掌聲)
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