While fire and sharp sticks became power plants and nuclear weapons

火と尖った棒だった

The biggest upgrade has happened to our brains

今は発電所や核兵器に変わり

Since the 1960's, the power of our brain machines has kept growing exponentially

人の脳は進歩した

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

1960年代からは機械が進歩を続け

But this process is about to meet its physical limits

年々より小型に より強力になった

Computer parts are approaching the size of an atom

だがここに物理的限界がきた

To understand why this is a problem, we have to clear up some basics

小さくなりすぎたのだ

In a Nutshell -By Kurzgesagt

この問題を基礎から説明していこう

A computer is made up of very simple components

コンピューターの構成要素は単純だ

doing very simple things

記憶 演算 制御の装置でできている

Representing data, the means of processing it, and control mechanisms

中にはチップ モジュール

Computer chips contains modules which contains logic gates, which contains transistors

論理ゲート トランジスタがある

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

トランジスタは単純なスイッチで

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

情報を流したり止めたりしている

This information is made up of bits

情報はビットで表され

Which can be set to either 0 or 1

０か１の値を取る

Combinations of several bits are used to represent more complex information

複数あれば より複雑な情報も表せる

Transistors are combined to create logic gates which still do very simple stuff

論理ゲートは単純な演算を行う

For example, an AND Gate sends an output of 1 if all of its inputs are 1 and a output of 0 otherwise

例えばANDゲートは

Combinations of logic gates finally form meaningful modules say for adding two numbers

全部１だと１を送り

Once you can add, you can also multiple

それ以外は０を送る

and once you can multiple, you can basically do anything

この集まりがモジュールとなり

Since all basic operations are literally simpler than first grade math

足し算ができる

You can imagine a computer as a group of 7 year old answering really basic math questions

足し算で掛け算ができ

A large enough bunch of them could compute anything

掛け算ができれば 何でもできる

from astrophysics to zelda

あるのは単純な計算の集まりだ

However, with parts getting tinier and tinier

７歳の子が集まって

Quantum physics are making things tricky

計算しているようなもの

In a nutshell, a transistor is just a electric switch

だがこれで

Electricity is electrons moving from one place to another

物理学やゼルダが可能になる

So, a switch is a passage that can block electrons from moving in one direction

物質が小さくなると

Today, a typical scale for Transistors is 14 nanometers

量子の性質が現れる

Which is about 8 time less than a HIV virus' diameter

トランジスタは電気のスイッチだ

and 500 times smaller than a red blood cells

電流は電子の動きであり

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

スイッチはこの流れを遮断している

Electrons may just transfer them to the other side of a blocked passage

今この大きさは14ナノメートルで

viral process called Quantum Tunneling

HIVウイルスの８分の１

In the quantum realm, physic works quite differently from the predictable way were used to

赤血球の500分の１しかない

and traditional computers just stop making sense

この大きさまで小さくなると

We are approaching a real physical barrier for our technological progress

電子はトンネル効果により

To solve this problem

壁をすり抜けてしまう

scientist are trying to use these unusual quantum properties to their advantage

量子の世界に通常の物理学は使えず

by building quantum computers

機械も使えなくなってしまう

In normal computers, bits are the smallest unit of information

技術は物理の限界に来たようだ

Quantum computers use Qubits which can also be set to one of two values

この問題を解決するため

A qubit can be any two level quantum system

新しい機械が考案された

such as a spin and a magnetic field or a single photon

量子コンピューターだ

0 and 1 are the system's possible states

普通はビットを使うところを

like the photons horizontal or vertical polarization

二つの状態を取れる

In the quantum world, the qubit doesn't have to be just one of those

量子ビットを使う

It can be any proportions of both states at once

量子が磁場であると同時に

This is called Superposition

粒子であることを利用する

But as soon as you test its value say by sending the photon through a filter

０と１の状態があり

It has to decide to be either vertically or horizontally polarized

これは光子の偏光状態に近い

So as long as it's unobserved

量子ビットは一つの状態ではなく

The qubit is in a superposition of probabilities for 0 and 1 and you can't predit which it'll be

一度に二つの状態で存在する

But the instant you measure it

これを重ね合わせと呼ぶ

It collapses into on of the definit states

光子は偏光板に通した瞬間

superposition is a game changer

垂直偏光か水平偏光かが決定される

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

観測されない限り量子ビットは

that's 16 possible combinations at which you can use just one

０と１の両方であると考えられ

Four qubits in superposition however, can be in all of those 16 combinations at once

特定の状態は観測した瞬間に決まる

This number grows exponentially with each extra qubit

重ね合わせが肝だ

20 of them can already store a million values in parallel

通常４ビットで情報を表すときは

A really wired and uninsured property qubits can have is Entanglement

16通りあるうちの一つしか使えない

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

でも量子ビットを使えば

no matter how far they are apart

16通りすべてを一度に表せる

This means when measuring just one entangled qubit, you can directly to use property of it's partner's

この増加は指数関数的だ

without having to look

20個使えば100万通りが並列できる

Qubit Manipulation is a mind bender as well

さらに量子もつれという現象がある

A normal logic gate gets a simple set of inputs and produce one definite output

二つの量子ビットが 離れていても

A quantum gate manipulates an input of superposition rotates probabilities

同時に同じ状態になる現象だ

and produces another superposition as its output

これにより一方を見るだけで

So a quantum computer sets up some qubits, apply quantum gates to entangle them and manipulate probabilities

もう一方の状態を知ることができる

then finally measures the outcome collapsing superposition to an actual seqence of 0s and 1s

量子ビットの操作は難しい

What this means is you get entire lot of calculations that are possible with your setup all done at the same time

論理ゲートでは

Ultimately you can only measure one of the results and it'll only probably be the one you want

一つの入力に一つの出力をしていた

So you might have to double check and try again

量子ゲートでは入力が回転して

But by cleverly exploiting superposition and entanglement

出力として別の重ね合わせが現れる

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

量子ビットに入れた入力が

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

量子ゲートを通ってもつれ

in some areas, they are vastly superior

それを観測すると

One of them is database searching

重ね合わせが崩れて結果がわかる

to find something in a database, a normal computer may have to test every single one of its entries

そこでは可能な計算が

Quantum algorithms need only the square root of that time

全部同時に行われている

which for large databases, is a huge difference

求めたい結果はその中の一つなので

The most famous use of quantum computers is ruining IT sercity

それを探し出す苦労がある

right now you are browsing email and banking data is being kept secure by an encryption safety system

だが量子の性質をうまく利用すれば

in which you give everyone a public key to encode messages only you can decode

超高速な計算が可能になるだろう

The problem is that this public key can actually be used to calculate your secret private key

私たちの生活に量子化は必要ないが

Luckily, doing the necessary math on any normal computer would literally take years of try and error

いくつかの領域では重要だ

But a quantum computer with exponential speed-up could do it in a breath

一つはデータベース検索

Another really exciting new use is simulations

普通はすべての要素を参照するが

Simulations of the quantum world are very intense on resources

量子のアルゴリズムでは

and even for bigger structures such as molecules they often lack accuracy

その平方根の時間で検索できる

So why not simulate quantum physics with actual quantum physics

一番大変なのは情報セキュリティだ

Quantum simulations could provide new insights on proteins that might revolutionize medicine

現在 ネットや銀行では

Right now we don't know if quantum computers will be just a specallized tool

公開鍵を使う方法によって

or a big revolution for humanity

情報を暗号化して守っている

We have no idea where the limits of technology are

だが公開鍵は計算すれば

and there's only one way to find out

解読できるものだ

This video is supported by the Australian Academy of Science

普通のコンピューターでは

which promotes and supports excellence in science

何年もかかる計算だが

Learn more about this topic and others like it at nova.org.au

量子コンピューターを使えば一瞬だ

It was a blast to work with them, so go check out their site!

シミュレーションにも使える

Our video are also made possible by your support on patreon.com

膨大な計算が必要な分野であり

If you want to support us and become part of the Kurzgesagt bird army, check out our Patreon page!

分子構造の解析などに役立つだろう

Subtitles by James Zhang [revisioned by Pietro Pasquero]

量子力学自体の研究にも当然使える