量子计算机（quantum computer）是一类遵循量子力学规律进行高速数学和逻辑运算、存储及处理量子信息的物理装置。当某个装置处理和计算的是量子信息，运行的是量子算法时，它就是量子计算机。量子计算机的概念源于对可逆计算机的研究。研究可逆计算机的目的是为了解决计算机中的能耗问题。

量子计算机光从百度百科上给出的内容看的话会让我们云里雾里。今天的TED演讲将会用十分钟的时间生动地让我们了解什么是量子计算机。

演讲内容如下

Let’s play a game.

咱们来玩个游戏。

Imagine that you are in Las Vegas,

想像你在拉斯维加斯，

in a casino,

在一间赌场裡，

and you decide to play a game on one of the casino’s computers,

你决定在其中一台电脑上玩游戏，

just like you might play solitaire or chess.

就像是玩纸牌或是下棋。

The computer can make moves in the game, just like a human player.

电脑也能移动游戏中的棋子， 和人类玩家一样。

This is a coin game.

这是一个硬币游戏。

It starts with a coin showing heads,

一开始，有一枚正面朝上的硬币，

and the computer will play first.

开局后，电脑先玩。

It can choose to flip the coin or not,

它可以选择是否抛掷这枚硬币，

but you don’t get to see the outcome.

但你不会知道结果如何。

Next, it’s your turn.

接著就轮到你。

You can also choose to flip the coin or not,

你也可以选择是否抛掷这枚硬币，

and your move will not be revealed to your opponent, the computer.

你的对手，也就是电脑， 同样不会知道这一轮的结果。

Finally, the computer plays again, and can flip the coin or not,

最后，又轮到电脑 选择是否抛掷硬币，

and after these three rounds,

经过三轮游戏之后，

the coin is revealed,

硬币的状态被揭示出来，

and if it is heads, the computer wins,

如果是正面朝上，就是电脑赢，

if it’s tails, you win.

如果是反面朝上，就是你赢。

So it’s a pretty simple game,

这是个很简单的游戏，

and if everybody plays honestly, and the coin is fair,

如果大家都不作弊， 且硬币也是均匀的，

then you have a 50 percent chance of winning this game.

那么你就有 50% 的机会获胜。

And to confirm that,

为了确认这一点，

I asked my students to play this game on our computers,

我让我的学生用我们的 电脑来玩这个游戏，

and after many, many tries,

在尝试非常非常多次之后，

their winning rate ended up being 50 percent, or close to 50 percent,

他们的胜率最后是 50% 或接近 50%，

as expected.

和预期的一样。

Sounds like a boring game, right?

听起来很无聊，对吧？

But what if you could play this game on a quantum computer?

但如果你能用量子电脑 来玩这个游戏，会怎样？

Now, Las Vegas casinos do not have quantum computers,

拉斯维加斯的赌场可没有量子电脑，

as far as I know,

据我所知是这样，

but IBM has built a working quantum computer.

但 IBM 已经打造出了一台 能够正常运转的量子电脑。

Here it is.

就是它。

But what is a quantum computer?

但是，量子电脑是什麽？

Well, quantum physics describes

嗯，量子物理是在描述

the behavior of atoms and fundamental particles,

原子和基本粒子的行为，

like electrons and photons.

比如电子和光子。

So a quantum computer operates

所以，量子电脑的运作方式

by controlling the behavior of these particles,

在于控制这些粒子的行为，

but in a way that is completely different from our regular computers.

但其做法和普通的电脑完全不同。

So a quantum computer is not just a more powerful version

量子电脑并不只是

of our current computers,

我们目前电脑的加强版，

just like a light bulb is not a more powerful candle.

就好像电灯泡并不是加强版的蜡烛。

You cannot build a light bulb by building better and better candles.

无论如何，蜡烛也不可能变成电灯泡。

A light bulb is a different technology,

电灯泡使用了一种不同的技术，

based on deeper scientific understanding.

它的基础是更深入的科学理解。

Similarly, a quantum computer is a new kind of device,

同样地，量子电脑也是一种新装置，

based on the science of quantum physics,

以量子物理为根据，

and just like a light bulb transformed society,

就如同电灯泡改变了人类社会，

quantum computers have the potential to impact

量子电脑也有潜力影响

so many aspects of our lives,

我们生活的方方面面，

including our security needs, our health care and even the internet.

包括我们的安全需求、 我们的医疗保健，甚至网际网路。

So companies all around the world are working to build these devices,

全世界的公司都在打造这类装置。

and to see what the excitement is all about,

要想看看它有多让人兴奋，

let’s play our game on a quantum computer.

咱们来用量子电脑玩这个游戏。

So I can log into IBM’s quantum computer from right here,

我可以从这裡登入到 IBM 的量子电脑，

which means I can play the game remotely,

也就表示我可以从远端玩这个游戏，

and so can you.

你也可以做到。

To make this happen, you may remember getting an email ahead of time, from TED,

为了让你们参与进来，你们可能记得，

asking you whether you would choose to flip the coin or not,

先前有收到 TED 寄的电子邮件，信上请你选择，

if you played the game.

如果你在玩这个游戏，

Well, actually, we asked you to choose between a circle or a square.

是否会选择抛掷硬币。事实上，我们在信上 是请你选择圆形或方形。

You didn’t know it, but your choice of circle meant "flip the coin,"

你当时并不知道，选择圆形 就表示「掷硬币」，

and your choice of square was "don’t flip."

选择方形就表示「不要掷」。

We received 372 responses.

我们收到了 372 个人的回覆。

Thank you.

谢谢你们。

That means we can play 372 games against the quantum computer

那就表示，我们可以用你们的选择，

using your choices.

跟量子电脑玩 372 场游戏。

And it’s a pretty fast game to play,

这个游戏一下就结束了，

so I can show you the results right here.

所以我可以把结果呈现在这裡。

Unfortunately, you didn’t do very well.

不幸的是，你们的战绩不太好。

(Laughter)

（笑声）

The quantum computer won almost every game.

量子电脑几乎全胜。

It lost a few only because of operational errors in the computer.

它输了几场，只是因为 电脑中的运算错误。

(Laughter)

（笑声）

So how did it achieve this amazing winning streak?

所以，它是如何取得 这惊人的一连串胜利的？

It seems like magic or cheating,

它就像魔术或作弊一样，

but actually, it’s just quantum physics in action.

但事实上，它只是量子物理的运作。

Here’s how it works.

它的运作方式如下。

A regular computer simulates heads or tails of a coin as a bit,

普通电脑用一个位元来 模拟硬币的正反面，

a zero or a one,

即 0 或是 1，

or a current flipping on and off inside your computer chip.

或记录当前是否选择抛掷硬币， 储存在你的电脑晶片中。

A quantum computer is completely different.

量子电脑则完全不同。

A quantum bit has a more fluid, nonbinary identity.

一个量子位元更具有 不固定性、非二进制的特质。

It can exist in a superposition, or a combination of zero and one,

它能存在于量子叠加态当中， 即 0 和 1 的组合当中，

with some probability of being zero and some probability of being one.

既有可能是 0，也有可能是 1。

In other words, its identity is on a spectrum.

换言之，它的真面目其实是一个范围。

For example, it could have a 70 percent chance of being zero

比如，它可能有 70% 的概率是 0，

and a 30 percent chance of being one

30% 的概率是 1，

or 80-20 or 60-40.

或 80% 与 20%， 60% 与 40%等。

The possibilities are endless.

存在无限的可能性。

The key idea here

这裡的关键在于，

is that we have to give up on precise values of zero and one

我们得要捨弃「只存在固定的 0 和 1」 的思考方式，

and allow for some uncertainty.

允许不确定性存在。

So during the game,

在游戏期间，

the quantum computer creates this fluid combination of heads and tails,

量子电脑会创造出正反两面

zero and one,

（0 和 1）的不固定性组合，

so that no matter what the player does,

所以，不论玩家选择什麽，

flip or no flip,

不论掷或不掷硬币，

the superposition remains intact.

这种 量子叠加态并不会改变。

It’s kind of like stirring a mixture of two fluids.

这有点像是在搅拌两种液体。

Whether or not you stir, the fluids remain in a mixture,

不论你搅或不搅， 两种液体都混合在一起。

but in its final move,

但在它的最后一轮游戏中，

the quantum computer can unmix the zero and one,

量子电脑能分离出 0 和 1，

perfectly recovering heads so that you lose every time.

将硬币完美地恢复成正面朝上， 所以你每次都会输。

(Laughter)

（笑声）

If you think this is all a bit weird, you are absolutely right.

如果你觉得这一切十分怪异， 那你一点儿也没错。

Regular coins do not exist in combinations of heads and tails.

普通硬币并不会以正面 和反面的组合形式存在。

We do not experience this fluid quantum reality

我们在日常生活中并不会经历

in our everyday lives.

这种不固定的、量子化的现实。

So if you are confused by quantum,

所以，如果量子让你困惑不解，

don’t worry, you’re getting it.

别担心，你其实正在明白它。

(Laughter)

（笑声）

But even though we don’t experience quantum strangeness,

但是，虽然我们没有 切身体验量子的不可思议，

we can see its very real effects in action.

我们可以看到它产生了 非常真实的影响。

You’ve seen the data for yourself.

你们已经亲眼看到资料了。

The quantum computer won

量子电脑会赢，

because it harnessed superposition and uncertainty,

是因为它利用量子叠加态和不确定性，

and these quantum properties are powerful,

这些量子特性非常强大，

not just to win coin games,

不仅能帮你赢得硬币游戏，

but also to build future quantum technologies.

也能用来建造未来的量子科技。

So let me give you three examples of potential applications

让我举三个例子， 说明那些有潜力的科技应用，

that could change our lives.

它们有可能改变我们的生活。

First of all, quantum uncertainty could be used to create private keys

首先，量子不确定性

for encrypting messages sent from one location to another

可用于私钥加密，

so that hackers could not secretly copy the key perfectly,

将两地之间传输的讯息进行加密，

because of quantum uncertainty.

因为量子不确定性，

They would have to break the laws of quantum physics

骇客就无法偷偷地複製完整密钥。

to hack the key.

他们若想盗用密钥，

So this kind of unbreakable encryption is already being tested by banks

就得打破量子物理的法则。

and other institutions worldwide.

全世界的银行和其他机构已经在测试

Today, we use more than 17 billion connected devices globally.

这种牢不可破的加密。

Just imagine the impact quantum encryption could have in the future.

现今，全球使用了超过 170 亿个接入网路的装置。

Secondly, quantum technologies could also transform health care and medicine.

想像一下，量子加密 在未来会有怎样的影响。

For example, the design and analysis of molecules for drug development

第二，量子科技也能转变 医疗保健和医学。

is a challenging problem today,

比如，在药物开发中， 设计和分析各种分子

and that’s because exactly describing and calculating

是现今很具挑战性的问题，

all of the quantum properties of all the atoms in the molecule

这是因为，要精确地描述和计算

is a computationally difficult task, even for our supercomputers.

分子中所有原子的全部量子特性，

But a quantum computer could do better,

是非常难以计算的， 即使对于超级电脑也同样。

because it operates using the same quantum properties

但量子电脑能做得更好，

as the molecule it’s trying to simulate.

因为它与它试图模拟的分子一样，

So future large-scale quantum simulations for drug development

使用了相同的量子特性来进行计算，

could perhaps lead to treatments for diseases like Alzheimer’s,

因此，对于药物开发， 未来的大规模量子模拟

which affects thousands of lives.

也许可以为阿兹海默症 之类的疾病找到治疗方式，

And thirdly, my favorite quantum application

影响成千上万的人。

is teleportation of information from one location to another

第三，是我最喜爱的量子应用，

without physically transmitting the information.

是将资讯从一个地点 即时传递到另一个地点，

Sounds like sci-fi, but it is possible,

但不需要实际传递。

because these fluid identities of the quantum particles

听起来很科幻，但这是有可能的，

can get entangled across space and time

因为量子粒子的这些不固定特质

in such a way that when you change something about one particle,

在时间和空间中 可能会纠缠在一起，

it can impact the other,

以至于当你改变了 其中的某一个粒子，

and that creates a channel for teleportation.

就会同时影响到其他粒子的状态， 这就成了量子通信的「通道」。

It’s already been demonstrated in research labs

在研究实验室裡已经展示它可行，

and could be part of a future quantum internet.

可能会成为未来量子 网际网路的一部分。

We don’t have such a network as yet,

我们目前尚无这样的网路，

but my team is working on these possibilities,

但我的团队正在努力实现它，

by simulating a quantum network on a quantum computer.

我们会在一台量子电脑上 模拟一个量子网路。

So we have designed and implemented some interesting new protocols

我们已经设计并实现了 一些有趣的、新的通讯协议，

such as teleportation among different users in the network

比如在网路上不同 用户之间传输讯息，

and efficient data transmission

以及高效的文件传输，

and even secure voting.

甚至还有安全的选举投票。

So it’s a lot of fun for me, being a quantum physicist.

因此，我身为量子物理学家， 觉得这非常有意思。

I highly recommend it.

我极力推荐它。

(Laughter)

（笑声）

We get to be explorers in a quantum wonderland.

我们有机会在量子仙境中当探险家。

Who knows what applications we will discover next.

谁知道接下来我们 会发现什麽新应用。

We must tread carefully and responsibly

当我们打造量子未来时，

as we build our quantum future.

我们必须要谨慎且可靠地向前迈进。

And for me, personally,

对我个人来说，

I don’t see quantum physics as a tool just to build quantum computers.

我认为量子物理并不只是 用来打造量子电脑的工具。

I see quantum computers as a way for us to probe the mysteries of nature

我认为量子电脑能协助我们 探索大自然的谜题，

and reveal more about this hidden world outside of our experiences.

并更深入地揭示出我们 无法体验的隐秘世界。

How amazing that we humans,

这是多麽不可思议，我们人类

with our relatively limited access to the universe,

对于宇宙的认识 和接触是相对受限的，

can still see far beyond our horizons

我们却单单靠著想像力和独创性，

just using our imagination and our ingenuity.

仍然能观察到远远 高于我们眼界的地方。

And the universe rewards us

而宇宙给我们的奖赏

by showing us how incredibly interesting and surprising it is.

就是让我们看到它是 多麽有趣、让人惊奇。

The future is fundamentally uncertain,

未来，本来就是不确定的，

and to me, that is certainly exciting.

但对我来说，我很确定， 它是让人兴奋的。

Thank you.

谢谢。

（部分图片、文章来源于网络，版权归原作者所有，如有侵权，请与我们联系）