量子计算机解析 —— 人类技术的极限：英语精读讲义

For most of our history, 短語搭配

在人类历史的大部分时间里，

human technology consisted of our brains,

人类的技术仅仅包括我们的大脑、

fire, and sharp sticks.

火，以及削尖的木棍。

While fire and sharp sticks became power plants and nuclear weapons, 語法

尽管火和尖木棍后来变成了发电厂和核武器，

the biggest upgrade has happened to our brains.

但最大的升级发生在我们的大脑上。

Since the 1960s,

自20世纪60年代以来，

the power of our brain machines has kept growing exponentially,

我们的“辅助大脑”机器的能力一直呈指数级增长，

allowing computers to get smaller and more powerful at the same time.

这让计算机在变得越来越小的同时，也越来越强大。

But this process is about to meet its physical limits. 講解

但这个过程即将迎来它的物理极限。

Computer parts are approaching the size of an atom.

计算机部件的大小正在逼近原子的尺寸。

To understand why this is a problem,

为了理解为什么这是个问题，

we have to clear up some basics. 短語動詞

我们必须先理清一些基础知识。

A computer is made up of very simple components 短語動詞

计算机是由非常简单的组件构成的，

doing very simple things,

做着非常简单的事情：

representing data,

表示数据，

the means of processing it,

处理数据的方法，

and control mechanisms.

以及控制机制。

Computer chips contain modules,

计算机芯片包含模块，

which contain logic gates, 語法

模块包含逻辑门，

which contain transistors.

逻辑门包含晶体管。

A transistor is the simplest form of a data processor in computers,

晶体管是计算机中最简单的数据处理器，

basically a switch that can either block or open the way for information coming through.

基本上就是一个开关，可以阻止或允许信息通过。

This information is made up of bits,

这些信息由比特组成，

which can be set to either zero or one.

比特可以被设置为0或1。

Combinations of several bits are used to represent more complex information.

几个比特的组合被用来表示更复杂的信息。

Transistors are combined to create logic gates,

晶体管组合起来创建了逻辑门，

which still do very simple stuff.

而逻辑门做的事情依然非常简单。

For example,

例如，

an AND gate sends an output of one if all of its inputs are one, 語法

一个与门（AND gate）如果所有输入都是1，它就输出1，

and an output of zero otherwise.

否则输出0。

Combinations of logic gates finally form meaningful modules,

逻辑门的组合最终形成了有实际意义的模块，

say for adding two numbers. 用詞

比如用于两个数字的加法。

Once you can add, 語法

一旦你能做加法，

you can also multiply,

你就能做乘法，

and once you can multiply,

一旦你能做乘法，

you can basically do anything.

你基本上就能做任何事了。

Since all basic operations are literally simpler than first grade math,

既然所有的基本运算都比一年级的数学还简单，

you can imagine a computer as a group of 7-year-olds answering really basic math questions.

你可以把计算机想象成一群7岁的孩子在回答非常基础的数学问题。

A large enough bunch of them could compute anything from astrophysics to Zelda. 表達脈絡

只要人数足够多，从天体物理学到《塞尔达》都能算出来。

However,

然而，

with parts getting tinier and tinier, 語法

随着零件变得越来越小，

quantum physics are making things tricky.

量子物理学让事情变得棘手起来。

In a nutshell, 習語

简而言之，

a transistor is just an electric switch.

晶体管只是一个电开关。

Electricity is electrons moving from one place to another,

电是电子从一个地方移动到另一个地方，

so a switch is a passage that can block electrons from moving in one direction. 語法

所以开关就是一条可以阻断电子朝某个方向移动的通道。

Today,

如今，

a typical scale for transistors is 14 nanometers,

晶体管的典型尺度是14纳米，

which is about eight times less than the HIV virus's diameter, 語法

大约是艾滋病病毒直径的八分之一，

and 500 times smaller than a red blood cell.

比红细胞小500倍。

As transistors are shrinking to the size of only a few atoms,

随着晶体管缩小到只有几个原子的大小，

electrons may just transfer themselves to the other side of a blocked passage

电子可能会穿过被阻断的通道，到达另一侧，

via a process called quantum tunneling. 講解

这个过程叫做量子隧穿。

In the quantum realm,

在量子领域，

physics works quite differently from the predictable ways we're used to, 語法

物理规律的运作方式与我们习惯的、可预测的方式截然不同，

and traditional computers just stop making sense. 短語搭配

传统的计算机也就变得不再合理了。

We are approaching a real physical barrier for our technological progress.

我们的技术进步正在逼近一个真正的物理障碍。

To solve this problem,

为了解决这个问题，

scientists are trying to use these unusual quantum properties to their advantage 短語搭配

科学家们试图利用这些不寻常的量子特性，

by building quantum computers.

通过制造量子计算机来将其转化为优势。

In normal computers,

在普通计算机中，

bits are the smallest units of information. 文化背景

比特是信息的最小单位。

Quantum computers use qubits,

量子计算机使用的是量子比特（qubit），

which can also be set to one of two values.

它同样可以被设置为两个值之一。

A qubit can be any two-level quantum system,

一个量子比特可以是任何双态量子系统，

such as a spin in a magnetic field,

比如磁场中的自旋，

or a single photon.

或是一个单光子。

Zero and one are this system's possible states,

0和1是这个系统的可能状态，

like the photon's horizontal or vertical polarization.

就像光子的水平或垂直偏振一样。

In the quantum world,

在量子世界中，

the qubit doesn't have to be in just one of those, 語法

量子比特不需要仅仅处于其中一种状态，

it can be in any proportions of both states at once.

它可以同时处于两种状态的任意比例之中。

This is called superposition. 文化背景

这被称为叠加态。

But as soon as you test its value, 語法

但只要你一测试它的值，

say by sending the photon through a filter,

比如让光子通过一个滤光片，

it has to decide to be either vertically or horizontally polarized.

它就必须决定是垂直偏振还是水平偏振。

So, as long as it's unobserved, 語法

因此，只要它未被观测，

the qubit is in a superposition of probabilities for zero and one,

量子比特就处于0和1概率的叠加态中，

and you can't predict which it will be. 語法

你无法预测它会是哪一个。

But the instant you measure it, 語法

但在你测量它的瞬间，

it collapses into one of the definite states. 用詞

它就会坍缩成一个明确的状态。

Superposition is a game-changer. 習語

叠加态是一个能改变游戏规则的特性。

Four classical bits can be in one of two to the power of four different configurations at a time. 用詞

四个经典比特在同一时间只能处于2的4次方种不同组合中的一种。

That's 16 possible combinations,

也就是16种可能的组合，

out of which you can use just one.

你只能使用其中的一种。

Four qubits in superposition, however,

然而，四个处于叠加态的量子比特，

can be in all of those 16 combinations at once.

可以同时处于这16种组合中。

This number grows exponentially with each extra qubit. 短語搭配

这个数字随着每增加一个量子比特而呈指数级增长。

20 of them can already store a million values in parallel. 用詞

20个量子比特就已经可以并行存储一百万个值。

A really weird and unintuitive property qubits can have is entanglement, 文化背景

量子比特能够拥有的一个非常奇特且违反直觉的特性是量子纠缠，

a close connection that makes each of the qubits react to a change in the other's state instantaneously,

这是一种密切的联系，使得每个量子比特都能对另一个状态的改变瞬间作出反应，

no matter how far they are apart. 語法

无论它们相隔多远。

This means that when measuring just one entangled qubit, 語法

这意味着当仅仅测量一个被纠缠的量子比特时，

you can directly deduce properties of its partners without having to look. 語法

你就可以直接推断出其伴侣的属性，而无需去查看。

Qubit manipulation is a mind-bender as well. 習語

量子比特的操作同样非常烧脑。

A normal logic gate gets a simple set of inputs

一个普通的逻辑门接收一组简单的输入，

and produces one definite output.

并产生一个确定的输出。

A quantum gate manipulates an input of superpositions,

而量子门操作的是叠加态的输入，

rotates probabilities,

它旋转概率，

and produces another superposition as its output.

并产生另一个叠加态作为其输出。

So, a quantum computer sets up some qubits, 短語動詞

所以，量子计算机设置了一些量子比特，

applies quantum gates to entangle them and manipulate probabilities,

应用量子门使它们纠缠并操作概率，

and finally measures the outcome,

最后测量结果，

collapsing superpositions to an actual sequence of zeros and ones.

将叠加态坍缩为0和1的实际序列。

What this means is that you get the entire lot of calculations 表達脈絡

这意味着，你的系统可以进行的所有计算

that are possible with your setup all done at the same time.

都在同一时间全部完成。

Ultimately, you can only measure one of the results,

最终，你只能测量其中一个结果，

and it will only probably be the one you want,

而且它可能只是你想要的那一个结果，

so you may have to double-check and try again.

所以你可能需要反复核对再试一次。

But by cleverly exploiting superposition and entanglement,

但通过巧妙地利用叠加和纠缠，

this can be exponentially more efficient than would ever be possible on a normal computer. 語法

这可以比普通计算机更加高效，呈指数级的提升。

So, while quantum computers will probably not replace our home computers,

因此，虽然量子计算机可能不会取代我们的家用电脑，

in some areas, they are vastly superior. 短語搭配

但在某些领域，它们却具有极大的优势。

One of them is database searching.

其中之一就是数据库搜索。

To find something in a database,

要在数据库中找到某个东西，

a normal computer may have to test every single one of its entries. 短語搭配

普通计算机可能要测试每一个词条。

Quantum algorithms need only the square root of that time, 語法

量子算法只需要测试该时间平方根的次数，

which for large databases is a huge difference.

对于庞大的数据库来说，这是一个巨大的差别。

The most famous use of quantum computers is ruining IT security.

量子计算机最著名的用途，就是摧毁IT安全系统。

Right now, your browsing, email, and banking data

目前，你的浏览、电子邮件和银行数据

is being kept secure by an encryption system 語法

都是被一个加密系统保护着，

in which you give everyone a public key 文化背景

在这个系统中，你给了每个人一个公钥，

to encode messages only you can decode.

用来编码只有你才能解码的信息。

The problem is that this public key

问题在于，这个公钥

can actually be used to calculate your secret private key.

实际上可以用来计算你的秘密私钥。

Luckily,

幸运的是，

doing the necessary math on any normal computer

在任何普通计算机上进行必要的数学计算，

would literally take years of trial and error. 講解

都需要耗费数年的反复试错。

But a quantum computer with exponential speedup

但一台具有指数级加速的量子计算机，

could do it in a breeze.

可以轻而易举地完成。

Another really exciting new use is simulations.

另一个非常激动人心的新用途是模拟。

Simulations of the quantum world are very intense on resources,

对量子世界进行模拟会极大地消耗资源，

and even for bigger structures such as molecules,

而且即便是对于像分子这样较大的结构，

they often lack accuracy.

它们也往往缺乏准确性。

So, why not simulate quantum physics 語氣意圖

那么，为什么不使用真实的量子物理

with actual quantum physics?

来模拟量子物理呢？

Quantum simulations could provide new insights on proteins

量子模拟可以提供关于蛋白质的新见解，

that might revolutionize medicine.

从而可能彻底改变医学。

Right now, we don't know if quantum computers 語法

目前，我们还不知道量子计算机

will be just a very specialized tool,

是只会成为一个非常专业的工具，

or a big revolution for humanity.

还是会成为人类的一场巨大革命。

We have no idea where the limits of technology are, 語法

我们完全不知道技术的极限在哪里，

and there's only one way to find out. 短語搭配

要找到答案，只有一种方法。

This video is supported by the Australian Academy of Science,

本视频由澳大利亚科学院支持，

which promotes and supports excellence in science.

该机构旨在促进并支持科学界的卓越发展。

Learn more about this topic and others like it

了解更多有关此话题及其他类似话题的信息，

at nova.org.au.

请访问 nova.org.au。

It was a blast to work with them. 習語

与他们合作非常愉快。

So, go check out their site.

所以，去看看他们的网站吧。

Our videos are also made possible by your support on patreon.com. 短語搭配

我们的视频也得益于你们在 patreon.com 上的支持才得以制作。

If you want to support us

如果你想支持我们，

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并成为 Kurzgesagt 鸟类大军的一员，

check out our Patreon page.

请访问我们的 Patreon 页面。