0:00:00.917,0:00:02.238
Let's play a game.

0:00:02.825,0:00:05.701
Imagine that you are in Las Vegas,

0:00:05.725,0:00:07.076
in a casino,

0:00:07.100,0:00:11.116
and you decide to play a game[br]on one of the casino's computers,

0:00:11.140,0:00:13.726
just like you might play[br]solitaire or chess.

0:00:14.520,0:00:17.670
The computer can make moves[br]in the game, just like a human player.

0:00:18.438,0:00:20.138
This is a coin game.

0:00:20.732,0:00:23.787
It starts with a coin showing heads,

0:00:23.811,0:00:25.612
and the computer will play first.

0:00:25.636,0:00:28.492
It can choose to flip the coin or not,

0:00:28.516,0:00:30.325
but you don't get to see the outcome.

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Next, it's your turn.

0:00:32.862,0:00:35.704
You can also choose[br]to flip the coin or not,

0:00:35.728,0:00:39.188
and your move will not be revealed[br]to your opponent, the computer.

0:00:39.737,0:00:43.736
Finally, the computer plays again,[br]and can flip the coin or not,

0:00:43.760,0:00:46.451
and after these three rounds,

0:00:46.475,0:00:48.404
the coin is revealed,

0:00:48.428,0:00:51.236
and if it is heads, the computer wins,

0:00:51.260,0:00:52.975
if it's tails, you win.

0:00:54.210,0:00:55.923
So it's a pretty simple game,

0:00:55.947,0:00:59.340
and if everybody plays honestly,[br]and the coin is fair,

0:00:59.364,0:01:03.126
then you have a 50 percent chance[br]of winning this game.

0:01:03.150,0:01:05.424
And to confirm that,

0:01:05.448,0:01:08.583
I asked my students to play[br]this game on our computers,

0:01:08.607,0:01:10.591
and after many, many tries,

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

0:01:14.679,0:01:16.330
as expected.

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Sounds like a boring game, right?

0:01:18.414,0:01:21.631
But what if you could play this game[br]on a quantum computer?

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Now, Las Vegas casinos[br]do not have quantum computers,

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as far as I know,

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but IBM has built[br]a working quantum computer.

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Here it is.

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But what is a quantum computer?

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Well, quantum physics describes

0:01:37.367,0:01:41.137
the behavior of atoms[br]and fundamental particles,

0:01:41.161,0:01:43.644
like electrons and photons.

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So a quantum computer operates

0:01:45.416,0:01:48.023
by controlling the behavior[br]of these particles,

0:01:48.047,0:01:51.713
but in a way that is completely different[br]from our regular computers.

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So a quantum computer[br]is not just a more powerful version

0:01:56.199,0:01:58.304
of our current computers,

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just like a light bulb[br]is not a more powerful candle.

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

0:02:07.048,0:02:09.263
A light bulb is a different technology,

0:02:09.287,0:02:11.941
based on deeper scientific understanding.

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Similarly, a quantum computer[br]is a new kind of device,

0:02:15.726,0:02:18.475
based on the science of quantum physics,

0:02:18.499,0:02:21.649
and just like a light bulb[br]transformed society,

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quantum computers[br]have the potential to impact

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so many aspects of our lives,

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

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

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and to see what[br]the excitement is all about,

0:02:37.521,0:02:39.671
let's play our game on a quantum computer.

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So I can log into IBM's[br]quantum computer from right here,

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which means I can play the game remotely,

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and so can you.

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

0:02:55.597,0:02:59.322
asking you whether you would choose[br]to flip the coin or not,

0:02:59.346,0:03:01.041
if you played the game.

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

0:03:05.957,0:03:09.799
You didn't know it, but your choice[br]of circle meant "flip the coin,"

0:03:09.823,0:03:11.980
and your choice of square[br]was "don't flip."

0:03:12.723,0:03:15.564
We received 372 responses.

0:03:15.588,0:03:16.778
Thank you.

0:03:16.802,0:03:21.270
That means we can play 372 games[br]against the quantum computer

0:03:21.294,0:03:22.922
using your choices.

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And it's a pretty fast game to play,

0:03:25.215,0:03:27.422
so I can show you the results right here.

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Unfortunately, you didn't do very well.

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(Laughter)

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The quantum computer won[br]almost every game.

0:03:36.159,0:03:39.881
It lost a few only because[br]of operational errors in the computer.

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(Laughter)

0:03:41.891,0:03:45.192
So how did it achieve[br]this amazing winning streak?

0:03:46.224,0:03:48.717
It seems like magic or cheating,

0:03:48.741,0:03:51.119
but actually, it's just[br]quantum physics in action.

0:03:51.780,0:03:53.356
Here's how it works.

0:03:53.380,0:03:58.832
A regular computer simulates[br]heads or tails of a coin as a bit,

0:03:58.856,0:04:00.511
a zero or a one,

0:04:00.535,0:04:04.415
or a current flipping on and off[br]inside your computer chip.

0:04:04.439,0:04:06.519
A quantum computer[br]is completely different.

0:04:07.250,0:04:11.763
A quantum bit has a more fluid,[br]nonbinary identity.

0:04:12.511,0:04:18.353
It can exist in a superposition,[br]or a combination of zero and one,

0:04:18.377,0:04:23.083
with some probability of being zero[br]and some probability of being one.

0:04:23.545,0:04:26.076
In other words,[br]its identity is on a spectrum.

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

0:04:30.617,0:04:32.953
and a 30 percent chance of being one

0:04:32.977,0:04:36.992
or 80-20 or 60-40.

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The possibilities are endless.

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The key idea here

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

0:04:45.287,0:04:47.128
and allow for some uncertainty.

0:04:47.737,0:04:49.388
So during the game,

0:04:49.412,0:04:54.159
the quantum computer creates[br]this fluid combination of heads and tails,

0:04:54.183,0:04:55.334
zero and one,

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so that no matter what the player does,

0:04:57.650,0:04:58.838
flip or no flip,

0:04:58.862,0:05:01.238
the superposition remains intact.

0:05:01.830,0:05:05.306
It's kind of like stirring[br]a mixture of two fluids.

0:05:05.714,0:05:10.099
Whether or not you stir,[br]the fluids remain in a mixture,

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but in its final move,

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the quantum computer[br]can unmix the zero and one,

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perfectly recovering heads[br]so that you lose every time.

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(Laughter)

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

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

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We do not experience[br]this fluid quantum reality

0:05:35.284,0:05:36.754
in our everyday lives.

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So if you are confused by quantum,

0:05:39.525,0:05:41.431
don't worry, you're getting it.

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(Laughter)

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But even though we don't experience[br]quantum strangeness,

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we can see its very real[br]effects in action.

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You've seen the data for yourself.

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The quantum computer won

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because it harnessed[br]superposition and uncertainty,

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and these quantum properties are powerful,

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not just to win coin games,

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but also to build[br]future quantum technologies.

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So let me give you three examples[br]of potential applications

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that could change our lives.

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

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for encrypting messages[br]sent from one location to another

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so that hackers could not[br]secretly copy the key perfectly,

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because of quantum uncertainty.

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They would have to break[br]the laws of quantum physics

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to hack the key.

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

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and other institutions worldwide.

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

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Just imagine the impact quantum encryption[br]could have in the future.

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

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

0:07:07.752,0:07:10.147
is a challenging problem today,

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and that's because[br]exactly describing and calculating

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all of the quantum properties[br]of all the atoms in the molecule

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is a computationally difficult task,[br]even for our supercomputers.

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But a quantum computer could do better,

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because it operates using[br]the same quantum properties

0:07:28.988,0:07:31.540
as the molecule it's trying to simulate.

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So future large-scale quantum[br]simulations for drug development

0:07:36.365,0:07:39.651
could perhaps lead to treatments[br]for diseases like Alzheimer's,

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which affects thousands of lives.

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And thirdly, my favorite[br]quantum application

0:07:45.416,0:07:50.075
is teleportation of information[br]from one location to another

0:07:50.099,0:07:53.141
without physically transmitting[br]the information.

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Sounds like sci-fi, but it is possible,

0:07:57.300,0:08:01.019
because these fluid identities[br]of the quantum particles

0:08:01.043,0:08:04.401
can get entangled across space and time

0:08:04.425,0:08:08.035
in such a way that when you change[br]something about one particle,

0:08:08.059,0:08:09.515
it can impact the other,

0:08:09.539,0:08:12.197
and that creates[br]a channel for teleportation.

0:08:13.039,0:08:15.648
It's already been demonstrated[br]in research labs

0:08:15.672,0:08:18.593
and could be part[br]of a future quantum internet.

0:08:19.219,0:08:22.566
We don't have such a network as yet,

0:08:22.590,0:08:25.494
but my team is working[br]on these possibilities,

0:08:25.518,0:08:29.367
by simulating a quantum network[br]on a quantum computer.

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So we have designed and implemented[br]some interesting new protocols

0:08:34.074,0:08:39.756
such as teleportation[br]among different users in the network

0:08:39.780,0:08:42.002
and efficient data transmission

0:08:42.026,0:08:43.629
and even secure voting.

0:08:44.502,0:08:47.381
So it's a lot of fun for me,[br]being a quantum physicist.

0:08:47.405,0:08:48.898
I highly recommend it.

0:08:48.922,0:08:50.880
(Laughter)

0:08:50.904,0:08:53.785
We get to be explorers[br]in a quantum wonderland.

0:08:53.809,0:08:56.693
Who knows what applications[br]we will discover next.

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We must tread carefully and responsibly

0:09:00.071,0:09:02.007
as we build our quantum future.

0:09:02.809,0:09:04.607
And for me, personally,

0:09:04.631,0:09:10.100
I don't see quantum physics as a tool[br]just to build quantum computers.

0:09:10.124,0:09:15.258
I see quantum computers as a way[br]for us to probe the mysteries of nature

0:09:15.282,0:09:19.194
and reveal more about this hidden world[br]outside of our experiences.

0:09:19.218,0:09:21.320
How amazing that we humans,

0:09:21.344,0:09:24.336
with our relatively limited[br]access to the universe,

0:09:24.360,0:09:26.994
can still see far beyond our horizons

0:09:27.018,0:09:29.598
just using our imagination[br]and our ingenuity.

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And the universe rewards us

0:09:32.552,0:09:36.480
by showing us how incredibly[br]interesting and surprising it is.

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The future is fundamentally uncertain,

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and to me, that is certainly exciting.

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Thank you.

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(Applause)