let's play a game
imagine that you are in Las Vegas in a
casino and you decide to play a game on
one of the casinos computers just like
you might play solitaire or chess the
computer can make moves in the game just
like a human player this is a coin game
it starts with a coin showing heads and
the computer will play first it can
choose to flip the coin or not but you
don't get to see the outcome next it's
your turn you can also choose to flip
the coin or not and your move will not
be revealed to your opponent the
computer
finally the computer plays again and can
flip the coin or not and after these
three rounds the coin is revealed and if
it is heads the computer wins if its
tail's
you win so it's a pretty simple game and
if everybody plays honestly and the coin
is fair then you have a 50% chance of
winning this game and to confirm that I
asked my students to play this game on
our computers and after many many tries
their winning rate ended up being 50% or
close to 50% as expected sounds like a
boring game right but what if you could
play this game on a quantum computer now
Las Vegas casinos do not have quantum
computers as far as I know but iBM has
built a working quantum computer here it
is but what is a quantum computer well
quantum physics describes the behavior
of atoms and fundamental particles like
electrons and photons so a quantum
computer operates by controlling the
behavior of these particles but in a way
that is completely different from our
regular computers so a quantum computer
is not just a more powerful version of
our current computers just like a
lightbulb is not a more powerful candle
you cannot build a light bulb by
building better and better candles a
light bulb is a different technology
based on deeper scientific understanding
similarly a quantum computer is a new
kind of device based on the science of
quantum physics and just like a light
bulb transformed Society quantum
computers have the potential to impact
so many aspects of our lives including
our security needs our healthcare and
even the Internet
so companies all around the world are
working to build these devices and to
see what the excitement is all about
let's play our game on a quantum
computer so I can log into IBM's quantum
computer from right here which means I
can play the game remotely and so can
you to make this happen
you may remember getting an email ahead
of time from Ted asking you whether you
would choose to flip the coin or not if
you played the game well actually we
asked you to choose between a circle or
a square you didn't know it but your
choice of circle meant flip the coin and
your choice of square was don't flip
we received 372 responses thank you that
means we can play 372 games against the
quantum computer using your choices and
it's a pretty fast game to play so I can
show you the results right here
unfortunately you didn't do very well
the quantum computer won almost every
game it lost a few only because of
operational errors in the computer so
how did it achieve this amazing winning
streak it seems like magic or cheating
but actually it's just quantum physics
in action here's how it works a regular
computer simulates heads or tails of a
coin as a bit a 0 or a 1 or a current
flipping on and off inside your computer
chip a quantum computer is completely
different a quantum bit has a more fluid
non-binary identity it can exist in a
superposition or a combination of 0 and
1 with some probability of being 0 and 1
some probability of being 1
in other words its identity is on a
spectrum for example it could have a 70%
chance of being 0 and a 30% chance of
being 1 or 84 8020 or 60/40 the
possibilities are endless the key idea
here is that we have to give up on
precise values of 0 and 1 and allow for
some uncertainty so during the game the
quantum computer creates this fluid
combination of heads and tails 0 & 1 so
that no matter what the player does flip
or no flip the superposition remains
intact it's kind of like stirring a
mixture of two fluids whether or not you
stir the fluids remain in a mixture but
in its final move the quantum computer
can unmix the 0 & 1
perfectly recovering a heads so that you
lose every time if you think this is all
a bit weird you are absolutely right
regular coins do not exist in
combinations of heads and tails we do
not experience this fluid quantum
reality in our everyday lives so if you
are confused by quantum don't worry
you're getting it but even though we
don't experience quantum strangeness we
can see it's very real effects in action
you've seen the data for yourself the
quantum computer one because it
harnessed superposition and uncertainty
and these quantum properties are
powerful not just to win coin games but
also to build future quantum
technologies so let me give you three
examples of potential applications that
could change our lives
first of all quantum uncertainty could
be used to create private keys for
encrypting messages sent from one
location to another so that hackers
could not secretly copy the key
perfectly because of quantum uncertainty
they would have to break the laws of
quantum physics
to hack the key so this kind of
unbreakable encryption is already being
tested by banks and other institutions
worldwide today we use more than 17
billion connected devices globally just
imagine the impact quantum encryption
could have in the future secondly
quantum technologies could also
transform healthcare and medicine for
example the design and analysis of
molecules for drug development is a
challenging problem today and that's
because exactly describing and
calculating all of the quantum
properties of all the atoms in the
molecule is a computationally difficult
task even for our supercomputers but a
quantum computer could do better because
it operates using the same quantum
properties as a molecule it's trying to
simulate so future large-scale quantum
simulations for drug development could
perhaps lead to treatments for diseases
like Alzheimer's which is affects
thousands of lives and thirdly my
favorite quantum application is
teleportation of information from one
location to another without physically
transmitting the information sounds like
sci-fi but it is possible because these
fluid identities of the quantum
particles can get entangled across space
and time in such a way that when you
change something about one particle it
can impact the other and that creates a
channel for teleportation it's already
been demonstrated in research labs and
could be part of a future quantum
Internet we don't have such an Network
as yet but my team is working on these
possibilities by simulating a quantum
network on a quantum computer so we have
designed and implemented some
interesting new protocols such as
teleportation among different users in
the network and efficient data
transmission and even secure voting so
it's a lot of fun for me being a quantum
physicist I highly recommend it
we get to be explorers in a quantum
Wonderland who knows what applications
we will discover next we must tread
carefully and responsibly as we build
our quantum future and for me personally
I don't see quantum physics as a tool
just to build quantum computers I see
quantum computers as a way for us to
probe the mysteries of nature and reveal
more about this hidden world outside of
our experiences how amazing that we
humans with our relatively limited
access to the universe can still see far
beyond our horizons just using our
imagination and our ingenuity and the
universe rewards us by showing us how
incredibly interesting and surprising it
is the future is fundamentally uncertain
and to me that is certainly exciting
thank you
[Applause]