TEDWomen 2018
Shohini Ghose: Quantum computing explained in 10 minutes
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A quantum computer isn't just a more powerful version of the computers we use today; it's something else entirely, based on emerging scientific understanding -- and more than a bit of uncertainty. Enter the quantum wonderland with TED Fellow Shohini Ghose and learn how this technology holds the potential to transform medicine, create unbreakable encryption and even teleport information.
Shohini Ghose - Quantum physicist, equity advocate
Shohini Ghose explores the strange quantum world of atoms and photons to understand the fundamental laws of the universe and harness them for quantum computing and communication -- and works to make science accessible and inclusive for people of all genders and backgrounds. Full bio
Shohini Ghose explores the strange quantum world of atoms and photons to understand the fundamental laws of the universe and harness them for quantum computing and communication -- and works to make science accessible and inclusive for people of all genders and backgrounds. Full bio
Double-click the English transcript below to play the video.
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Let's play a game.
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Imagine that you are in Las Vegas,
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in a casino,
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and you decide to play a game
on one of the casino's computers,
on one of the casino's computers,
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just like you might play
solitaire or chess.
solitaire or chess.
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The computer can make moves
in the game, just like a human player.
in the game, just like a human player.
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This is a coin game.
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It starts with a coin showing heads,
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and the computer will play first.
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It can choose to flip the coin or not,
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but you don't get to see the outcome.
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Next, it's your turn.
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You can also choose
to flip the coin or not,
to flip the coin or not,
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and your move will not be revealed
to your opponent, the computer.
to your opponent, the computer.
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Finally, the computer plays again,
and can flip the coin or not,
and can flip the coin or not,
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and after these three rounds,
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the coin is revealed,
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and if it is heads, the computer wins,
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if it's tails, you win.
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So it's a pretty simple game,
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and if everybody plays honestly,
and the coin is fair,
and the coin is fair,
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then you have a 50 percent chance
of winning this game.
of winning this game.
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And to confirm that,
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I asked my students to play
this game on our computers,
this game on our computers,
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and after many, many tries,
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their winning rate ended up
being 50 percent, or close to 50 percent,
being 50 percent, or close to 50 percent,
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as expected.
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Sounds like a boring game, right?
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But what if you could play this game
on a quantum computer?
on a quantum computer?
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Now, Las Vegas casinos
do not have quantum computers,
do not have quantum computers,
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as far as I know,
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but IBM has built
a working quantum computer.
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
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the behavior of atoms
and fundamental particles,
and fundamental particles,
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like electrons and photons.
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So a quantum computer operates
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by controlling the behavior
of these particles,
of these particles,
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but in a way that is completely different
from our regular computers.
from our regular computers.
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So a quantum computer
is not just a more powerful version
is not just a more powerful version
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of our current computers,
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just like a light bulb
is not a more powerful candle.
is not a more powerful candle.
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You cannot build a light bulb
by building better and better candles.
by building better and better candles.
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A light bulb is a different technology,
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based on deeper scientific understanding.
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Similarly, a quantum computer
is a new kind of device,
is a new kind of device,
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based on the science of quantum physics,
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and just like a light bulb
transformed society,
transformed society,
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quantum computers
have the potential to impact
have the potential to impact
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so many aspects of our lives,
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including our security needs,
our health care and even the internet.
our health care and even the internet.
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So companies all around the world
are working to build these devices,
are working to build these devices,
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and to see what
the excitement is all about,
the excitement is all about,
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let's play our game on a quantum computer.
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So I can log into IBM's
quantum computer from right here,
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
getting an email ahead of time, from TED,
getting an email ahead of time, from TED,
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asking you whether you would choose
to flip the coin or not,
to flip the coin or not,
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if you played the game.
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Well, actually, we asked you to choose
between a circle or a square.
between a circle or a square.
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You didn't know it, but your choice
of circle meant "flip the coin,"
of circle meant "flip the coin,"
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and your choice of square
was "don't flip."
was "don't flip."
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We received 372 responses.
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Thank you.
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That means we can play 372 games
against the quantum computer
against the quantum computer
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using your choices.
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And it's a pretty fast game to play,
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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
almost every game.
almost every game.
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It lost a few only because
of operational errors in the computer.
of operational errors in the computer.
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(Laughter)
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So how did it achieve
this amazing winning streak?
this amazing winning streak?
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It seems like magic or cheating,
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but actually, it's just
quantum physics in action.
quantum physics in action.
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Here's how it works.
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A regular computer simulates
heads or tails of a coin as a bit,
heads or tails of a coin as a bit,
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a zero or a one,
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or a current flipping on and off
inside your computer chip.
inside your computer chip.
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A quantum computer
is completely different.
is completely different.
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A quantum bit has a more fluid,
nonbinary identity.
nonbinary identity.
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It can exist in a superposition,
or a combination of zero and one,
or a combination of zero and one,
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with some probability of being zero
and some probability of being one.
and some probability of being one.
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In other words,
its identity is on a spectrum.
its identity is on a spectrum.
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For example, it could have
a 70 percent chance of being zero
a 70 percent chance of being zero
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and a 30 percent chance of being one
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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
on precise values of zero and one
on precise values of zero and one
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and allow for some uncertainty.
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So during the game,
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the quantum computer creates
this fluid combination of heads and tails,
this fluid combination of heads and tails,
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zero and one,
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so that no matter what the player does,
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flip or no flip,
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the superposition remains intact.
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It's kind of like stirring
a mixture of two fluids.
a mixture of two fluids.
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Whether or not you stir,
the fluids remain in a mixture,
the fluids remain in a mixture,
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but in its final move,
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the quantum computer
can unmix the zero and one,
can unmix the zero and one,
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perfectly recovering heads
so that you lose every time.
so that you lose every time.
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(Laughter)
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If you think this is all a bit weird,
you are absolutely right.
you are absolutely right.
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Regular coins do not exist
in combinations of heads and tails.
in combinations of heads and tails.
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We do not experience
this fluid quantum reality
this fluid quantum reality
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in our everyday lives.
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So if you are confused by quantum,
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don't worry, you're getting it.
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(Laughter)
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But even though we don't experience
quantum strangeness,
quantum strangeness,
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we can see its very real
effects in action.
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
superposition and uncertainty,
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
future quantum technologies.
future quantum technologies.
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So let me give you three examples
of potential applications
of potential applications
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that could change our lives.
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First of all, quantum uncertainty
could be used to create private keys
could be used to create private keys
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for encrypting messages
sent from one location to another
sent from one location to another
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so that hackers could not
secretly copy the key perfectly,
secretly copy the key perfectly,
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because of quantum uncertainty.
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They would have to break
the laws of quantum physics
the laws of quantum physics
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to hack the key.
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So this kind of unbreakable encryption
is already being tested by banks
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
connected devices globally.
connected devices globally.
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Just imagine the impact quantum encryption
could have in the future.
could have in the future.
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Secondly, quantum technologies could also
transform health care and medicine.
transform health care and medicine.
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For example, the design and analysis
of molecules for drug development
of molecules for drug development
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is a challenging problem today,
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and that's because
exactly describing and calculating
exactly describing and calculating
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all of the quantum properties
of all the atoms in the molecule
of all the atoms in the molecule
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is a computationally difficult task,
even for our supercomputers.
even for our supercomputers.
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But a quantum computer could do better,
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because it operates using
the same quantum properties
the same quantum properties
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as the molecule it's trying to simulate.
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So future large-scale quantum
simulations for drug development
simulations for drug development
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could perhaps lead to treatments
for diseases like Alzheimer's,
for diseases like Alzheimer's,
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which affects thousands of lives.
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And thirdly, my favorite
quantum application
quantum application
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is teleportation of information
from one location to another
from one location to another
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without physically transmitting
the information.
the information.
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Sounds like sci-fi, but it is possible,
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because these fluid identities
of the quantum particles
of the quantum particles
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can get entangled across space and time
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in such a way that when you change
something about one particle,
something about one particle,
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it can impact the other,
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and that creates
a channel for teleportation.
a channel for teleportation.
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It's already been demonstrated
in research labs
in research labs
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and could be part
of a future quantum internet.
of a future quantum internet.
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We don't have such a network as yet,
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but my team is working
on these possibilities,
on these possibilities,
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by simulating a quantum network
on a quantum computer.
on a quantum computer.
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So we have designed and implemented
some interesting new protocols
some interesting new protocols
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such as teleportation
among different users in the network
among different users in the network
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and efficient data transmission
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and even secure voting.
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So it's a lot of fun for me,
being a quantum physicist.
being a quantum physicist.
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I highly recommend it.
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(Laughter)
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We get to be explorers
in a quantum wonderland.
in a quantum wonderland.
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Who knows what applications
we will discover next.
we will discover next.
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We must tread carefully and responsibly
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as we build our quantum future.
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And for me, personally,
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I don't see quantum physics as a tool
just to build quantum computers.
just to build quantum computers.
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I see quantum computers as a way
for us to probe the mysteries of nature
for us to probe the mysteries of nature
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and reveal more about this hidden world
outside of our experiences.
outside of our experiences.
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How amazing that we humans,
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with our relatively limited
access to the universe,
access to the universe,
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can still see far beyond our horizons
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just using our imagination
and our ingenuity.
and our ingenuity.
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And the universe rewards us
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by showing us how incredibly
interesting and surprising it is.
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)
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ABOUT THE SPEAKER
Shohini Ghose - Quantum physicist, equity advocateShohini Ghose explores the strange quantum world of atoms and photons to understand the fundamental laws of the universe and harness them for quantum computing and communication -- and works to make science accessible and inclusive for people of all genders and backgrounds.
Why you should listen
As Shohini Ghose writes: "I've always wanted to be an explorer. As a girl I was inspired by Rakesh Sharma, the first Indian to go to space. I haven't made it to space yet, but I did become an explorer of a strange and exciting new world -- the quantum world of microscopic particles such as electrons and photons. I'm a theoretical physicist who examines how the laws of quantum physics can be harnessed to transform computation and communication. My colleagues and I made the first-ever observations of cesium atoms that demonstrated a connection between chaos theory and quantum entanglement.
"The activist in me questions why only three women have ever won the Nobel Prize in physics. I am passionate about addressing gender issues in science and recently founded the Laurier Centre for Women in Science, the first centre of its kind in Canada. I also work to create a vibrant and inclusive physics community in Canada as the vice president of the Canadian Association of Physicists. I love teaching and have co-authored Canada's largest selling introductory astronomy textbook."
Shohini Ghose | Speaker | TED.com