[Music]
I want to ask you a question what
happened on the 29th of October 1969
landing on the moon close but on this
day something equally enormous happened
namely the first message was sent over
the Internet
so let me explain just how difficult it
actually was to send that first message
so the internet was super tiny and at
half-past 10:00 in the evening
researchers had gathered down in Los
Angeles and at Stanford up in Menlo Park
to send the first test message and they
had agreed to send the message log in
like looking into a remote computer and
because this was challenging they called
each other on the phone make sure
message arrived so there were these guys
down in Los Angeles at the computer and
they type the first letter L and he
asked on the phone did you see the L an
excited message comes back yes yes we
see the L and we sent the first letter
over the internet they typed the second
letter Bo and asked again did you see
the O and he said yes we also see the O
and they typed the letter G and the
system crashed
so the Internet is a little bit larger
now and we use it to send vast
quantities of data I’ve recently moved
into a new apartment and just like in
many places in the world I sign up for
internet like you sign up for power or
water the Internet is everywhere and it
certainly changed the way that we live
today so I’m working on a quantum
internet because I believe that it will
similarly revolutionize the world so of
course you’re asking now what is this
quantum Internet so on the surface it
looks a lot like a classical Internet
there’s computers and we’re gonna send
data from one computer to another only
on the quantum Internet this is a
quantum computer and I’m sending quantum
data quantum bits or qubits from one
place to another so these qubits are
pretty special for example we cannot
copy a qubit unlike a classical bit that
can be either 0 or 1
a qubit can be both 0 and 1 at the same
time so you might imagine that instead
of sending pictures of a cat that is
either dead or alive we are going to
send a Schrodinger’s cat that is both
dead and alive or 0 and 1 at the same
time so these qubits are pretty cool but
it brings us to the question why do we
want to send them around so a quantum
Internet has many applications that are
impossible on the Internet today it can
make many things more efficient and in
fact to use the quantum Internet
you also don’t need to have a large
quantum computer at home
so probably the most famous application
of a quantum internet is to use it for
secure communication so secure
communication means that I am going to
send data to you like my credit card
information or maybe state secrets and I
want that no one is able to listen into
this communication a quantum internet
allows us to use quantum key
distribution that enables secure
communication whose security relies only
on the laws of quantum mechanics in
particular it’s secure even if some
eavesdropper was trying to snoop into
our communication has a quantum computer
and it remains secure even if this
eavesdropper buys a quantum computer
tomorrow so that’s pretty nice but the
quantum Internet has many other possibly
less well-known applications which
personally I find probably even more
exciting using a quantum Internet we can
use a quantum computer in the cloud so
quantum computers promise to solve many
problems much faster than a classical
computer in particular we think that
they’re extremely good at simulating
problems in quantum chemistry so you
might imagine that in the future if you
want to explore a new material or a new
medicine you don’t first go into the lab
and with some hugely long time consuming
experiment but you’re first going to run
the quick simulation on your quantum
computer to see whether that makes sense
at all now quantum computers are pretty
expensive I sort of expected I will
actually be dead by the time that we all
have a quantum computer at home or in
our office but of course we want to use
this computing power
so the first quantum computers are
likely going to be somewhere in the
cloud and I’m going to pay say to use
that for an hour
now maybe I want to use this quantum
computer to perform a simulation on some
proprietary material or possibly even my
own DNA so I don’t want to give my DNA
to this quantum computer so it turns out
that using a quantum internet we can use
this remote quantum computer in the
cloud securely in the sense that it has
no idea what we’re going to use it for
quantum Internet can also do all kinds
of other cool things like it’s good at
synchronizing clocks much more
accurately than we can do classically it
can be used to enhance password
identification to some server far away
and curiously we can even use it to play
better at an online game so what is it
about these qubits that is so special
that it enables all these applications
to qubits can be entangled using a
quantum Internet
now entanglement also still sounds
pretty mysterious but there’s actually
only two features of quantum
entanglement that lie at the bottom of
all of these applications so if you
understand these two features you will
have a pretty good intuition of what a
quantum Internet is good for so what are
these two features so the first one is
called maximum coordination let’s say
I’ve used the quantum Internet to
entangle a qubit here in Vienna with
some cubed far away somewhere down in
Sydney and I’m going to perform a
measurement on my qubits and let’s
imagine a friend down in sydney performs
exactly the same measurement now if you
make the same measurement we will get
the same measurement outcome
instantaneously you can think of a
measurement as asking a question to a
qubit I can ask qubits are you pointing
left
or are you pointing right and if I ask
the question to Mike you eat here in
Vienna and my friend asks the same
question down in Sydney then if I see
left he will see left and if I see right
he was he right
and this happens instantaneously even
though the answer is not determined
ahead of time and the cool thing is that
it actually works for any question that
we might have asked to disk you bit if I
had asked you red or green we would have
seen exactly the same we get always the
same answer so entanglement is maximally
coordinated and it is this feature that
makes it naturally so suited for tasks
that require coordination or
synchronization so remember I said there
were two features of quantum
entanglement so what is this second
feature the second feature of quantum
entanglement is that it’s inherently
private if I have two qubits and they’re
completely entangled with each other
then it’s physically impossible for any
other qubit or actually anything else in
the universe to have any share of this
entanglement this means that if I have a
qubit that is completely entangled with
your qubit no one else can have a share
of the entanglement our to entangle
qubits form a private connection that no
one else can share so entanglement
cannot be shared and it’s inherently
private and it’s this feature that makes
it naturally very suited for secure
communication remember these two
features
it’s maximally coordinated and
inherently private so now I’ve told you
all these things about qubits and
entanglement but given that quantum
entanglement is so cool you might ask
why don’t we have a quantum intimate yet
it turns out that we can actually send
qubits over short distances
you can go online and actually buy a
commercially available box that performs
quantum key distribution quantum secure
communication over standard telecom
fiber over distances of roughly 100
kilometers so the real challenge in
building a quantum Internet is to get
these qubits to travel further than
these hundred kilometers so of course
you might be asking why is it so
difficult for these qubits to traverse
long distances if I wanted to send a
qubit down a communication line we are
sending a single photon one particle of
light so you can imagine that if I take
one single particle of light and I send
it down a communication line very soon
it will be lost
remember that also qubits cannot be
copied so if it’s lost it’s gone
I cannot resend and try again so how can
we hope to send these qubits over long
distances so fortunately as as I
mentioned we can actually send them over
short distances so let’s put like a box
in the middle and the box is not so far
away from the left and it’s not so far
away from the right namely close enough
that I can send qubits both from the
left and from the right to the box all
right
let’s try that what we’re going to do is
we’re going to take two entangled qubits
on their left and I’m going to send one
of them to the box box is not far away
so we can do that I’m going to take
another two qubits which are entangled
I’m going to send one of them to the box
so now we have entanglement with this
box so the cool thing is that there is a
procedure called entanglement swapping
with which we can glue this entanglement
together and create entanglement over
the entire distance that’s pretty cool
so such a box is called a quantum
repeater and we can use it to make
entanglement over long distances but
you’re probably saying what about this
entanglement you promised us that we
could send my Schrodinger cats this
particular data qubits that I want to
send somewhere else so there’s a nice
feature of quantum that if we have
entanglement we can now send a data
qubit by teleporting it across so we I
take my yellow data qubit and i teleport
it to the other side
so this way we can send qubits over long
distances so we’re probably saying you
know this talk is getting more
fantastical by the minute
first there are these qubits now are we
even going to teleport them around so we
are actually actively working on this
box
the quantum repeater and by 2020 we
wanted to have the first demonstration
network in the Netherlands that
showcases this box
the quantum repeater it might become the
first quantum Internet in the world that
actually connects small quantum
computers small quantum processors in
such a way that we can send qubits from
any of these quantum computers to
another we can make entanglement between
any of the
two cities so you can sort of think that
we are now on the edge of the quantum
1969 and in 2020 we want to send the
first quantum message over what might be
the first quantum Internet thank you
very much
[Applause]
I want to ask you a question what
happened on the 29th of October 1969
landing on the moon close but on this
day something equally enormous happened
namely the first message was sent over
the Internet
so let me explain just how difficult it
actually was to send that first message
so the internet was super tiny and at
half-past 10:00 in the evening
researchers had gathered down in Los
Angeles and at Stanford up in Menlo Park
to send the first test message and they
had agreed to send the message log in
like looking into a remote computer and
because this was challenging they called
each other on the phone make sure
message arrived so there were these guys
down in Los Angeles at the computer and
they type the first letter L and he
asked on the phone did you see the L an
excited message comes back yes yes we
see the L and we sent the first letter
over the internet they typed the second
letter Bo and asked again did you see
the O and he said yes we also see the O
and they typed the letter G and the
system crashed
so the Internet is a little bit larger
now and we use it to send vast
quantities of data I’ve recently moved
into a new apartment and just like in
many places in the world I sign up for
internet like you sign up for power or
water the Internet is everywhere and it
certainly changed the way that we live
today so I’m working on a quantum
internet because I believe that it will
similarly revolutionize the world so of
course you’re asking now what is this
quantum Internet so on the surface it
looks a lot like a classical Internet
there’s computers and we’re gonna send
data from one computer to another only
on the quantum Internet this is a
quantum computer and I’m sending quantum
data quantum bits or qubits from one
place to another so these qubits are
pretty special for example we cannot
copy a qubit unlike a classical bit that
can be either 0 or 1
a qubit can be both 0 and 1 at the same
time so you might imagine that instead
of sending pictures of a cat that is
either dead or alive we are going to
send a Schrodinger’s cat that is both
dead and alive or 0 and 1 at the same
time so these qubits are pretty cool but
it brings us to the question why do we
want to send them around so a quantum
Internet has many applications that are
impossible on the Internet today it can
make many things more efficient and in
fact to use the quantum Internet
you also don’t need to have a large
quantum computer at home
so probably the most famous application
of a quantum internet is to use it for
secure communication so secure
communication means that I am going to
send data to you like my credit card
information or maybe state secrets and I
want that no one is able to listen into
this communication a quantum internet
allows us to use quantum key
distribution that enables secure
communication whose security relies only
on the laws of quantum mechanics in
particular it’s secure even if some
eavesdropper was trying to snoop into
our communication has a quantum computer
and it remains secure even if this
eavesdropper buys a quantum computer
tomorrow so that’s pretty nice but the
quantum Internet has many other possibly
less well-known applications which
personally I find probably even more
exciting using a quantum Internet we can
use a quantum computer in the cloud so
quantum computers promise to solve many
problems much faster than a classical
computer in particular we think that
they’re extremely good at simulating
problems in quantum chemistry so you
might imagine that in the future if you
want to explore a new material or a new
medicine you don’t first go into the lab
and with some hugely long time consuming
experiment but you’re first going to run
the quick simulation on your quantum
computer to see whether that makes sense
at all now quantum computers are pretty
expensive I sort of expected I will
actually be dead by the time that we all
have a quantum computer at home or in
our office but of course we want to use
this computing power
so the first quantum computers are
likely going to be somewhere in the
cloud and I’m going to pay say to use
that for an hour
now maybe I want to use this quantum
computer to perform a simulation on some
proprietary material or possibly even my
own DNA so I don’t want to give my DNA
to this quantum computer so it turns out
that using a quantum internet we can use
this remote quantum computer in the
cloud securely in the sense that it has
no idea what we’re going to use it for
quantum Internet can also do all kinds
of other cool things like it’s good at
synchronizing clocks much more
accurately than we can do classically it
can be used to enhance password
identification to some server far away
and curiously we can even use it to play
better at an online game so what is it
about these qubits that is so special
that it enables all these applications
to qubits can be entangled using a
quantum Internet
now entanglement also still sounds
pretty mysterious but there’s actually
only two features of quantum
entanglement that lie at the bottom of
all of these applications so if you
understand these two features you will
have a pretty good intuition of what a
quantum Internet is good for so what are
these two features so the first one is
called maximum coordination let’s say
I’ve used the quantum Internet to
entangle a qubit here in Vienna with
some cubed far away somewhere down in
Sydney and I’m going to perform a
measurement on my qubits and let’s
imagine a friend down in sydney performs
exactly the same measurement now if you
make the same measurement we will get
the same measurement outcome
instantaneously you can think of a
measurement as asking a question to a
qubit I can ask qubits are you pointing
left
or are you pointing right and if I ask
the question to Mike you eat here in
Vienna and my friend asks the same
question down in Sydney then if I see
left he will see left and if I see right
he was he right
and this happens instantaneously even
though the answer is not determined
ahead of time and the cool thing is that
it actually works for any question that
we might have asked to disk you bit if I
had asked you red or green we would have
seen exactly the same we get always the
same answer so entanglement is maximally
coordinated and it is this feature that
makes it naturally so suited for tasks
that require coordination or
synchronization so remember I said there
were two features of quantum
entanglement so what is this second
feature the second feature of quantum
entanglement is that it’s inherently
private if I have two qubits and they’re
completely entangled with each other
then it’s physically impossible for any
other qubit or actually anything else in
the universe to have any share of this
entanglement this means that if I have a
qubit that is completely entangled with
your qubit no one else can have a share
of the entanglement our to entangle
qubits form a private connection that no
one else can share so entanglement
cannot be shared and it’s inherently
private and it’s this feature that makes
it naturally very suited for secure
communication remember these two
features
it’s maximally coordinated and
inherently private so now I’ve told you
all these things about qubits and
entanglement but given that quantum
entanglement is so cool you might ask
why don’t we have a quantum intimate yet
it turns out that we can actually send
qubits over short distances
you can go online and actually buy a
commercially available box that performs
quantum key distribution quantum secure
communication over standard telecom
fiber over distances of roughly 100
kilometers so the real challenge in
building a quantum Internet is to get
these qubits to travel further than
these hundred kilometers so of course
you might be asking why is it so
difficult for these qubits to traverse
long distances if I wanted to send a
qubit down a communication line we are
sending a single photon one particle of
light so you can imagine that if I take
one single particle of light and I send
it down a communication line very soon
it will be lost
remember that also qubits cannot be
copied so if it’s lost it’s gone
I cannot resend and try again so how can
we hope to send these qubits over long
distances so fortunately as as I
mentioned we can actually send them over
short distances so let’s put like a box
in the middle and the box is not so far
away from the left and it’s not so far
away from the right namely close enough
that I can send qubits both from the
left and from the right to the box all
right
let’s try that what we’re going to do is
we’re going to take two entangled qubits
on their left and I’m going to send one
of them to the box box is not far away
so we can do that I’m going to take
another two qubits which are entangled
I’m going to send one of them to the box
so now we have entanglement with this
box so the cool thing is that there is a
procedure called entanglement swapping
with which we can glue this entanglement
together and create entanglement over
the entire distance that’s pretty cool
so such a box is called a quantum
repeater and we can use it to make
entanglement over long distances but
you’re probably saying what about this
entanglement you promised us that we
could send my Schrodinger cats this
particular data qubits that I want to
send somewhere else so there’s a nice
feature of quantum that if we have
entanglement we can now send a data
qubit by teleporting it across so we I
take my yellow data qubit and i teleport
it to the other side
so this way we can send qubits over long
distances so we’re probably saying you
know this talk is getting more
fantastical by the minute
first there are these qubits now are we
even going to teleport them around so we
are actually actively working on this
box
the quantum repeater and by 2020 we
wanted to have the first demonstration
network in the Netherlands that
showcases this box
the quantum repeater it might become the
first quantum Internet in the world that
actually connects small quantum
computers small quantum processors in
such a way that we can send qubits from
any of these quantum computers to
another we can make entanglement between
any of the
two cities so you can sort of think that
we are now on the edge of the quantum
1969 and in 2020 we want to send the
first quantum message over what might be
the first quantum Internet thank you
very much
[Applause]
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