Transcriber: Robert Tucker
Reviewer: Ariana Bleau Lugo
I am indeed a theoretical physicist
and I'll tell you about quantum computers.
Not to worry, I mean I could give
this title for the layman
which is to say: "How your gadgets
got to be the way they are,
and how they'll be
completely different in the future."
So, I'm the kind of person who actually
tries to make these gadgets,
and tries to make them different,
but I should say
that a physicist usually,
one like me anyway,
does not actually consciously say,
"I'm going to make gadgets,
I'm going to make money."
It's more that I am a kind of person
who likes to figure out,
and the people who made computers
and continue to make computers,
like to figure out how things work,
like to explain it to other people,
and then try to figure out how
they could work completely differently.
So, I'm going to take you
through that process,
I'm going to talk about
how computers arose
and how we might make a big transition
into a new kind of computer.
I'll begin with some other examples
which are not computers,
not computer technology but other kinds
of industries and technologies,
talk about how innovation is involved
in making them what they are,
and how it's important
in their transformations
that we accept new ideas, accept change,
and accept the fact that sometimes
they have to be ruthlessly changed
or done away with in order that
new things can come along.
So, I'm going to begin
with one of those examples.
It involves an immigrant from here --
Johann Brill came from Germany
to America to Philadelphia
as a humble workman
in the 19th century
and by, you know, dint of good luck
and hard work and brilliance
he became a great magnate of industry
and he became, or his company became
the biggest manufacturer of rail cars
in the United States,
mostly of urban rail cars and streetcars.
And the reason why this is
a special story for me
is that this factory,
this lithograph you can see,
this giant factory complex,
was just a few blocks
from where I grew up.
So, I was very connected
with this particular factory.
And this factory prospered
under Herr Brill,
and afterwards under his son
for many decades,
but it didn't prosper very long,
or it had ceased to be vital
around the time that I was born.
And I remember being taken as a child
to a bridge where you could
look over this site,
and it was still there, but it was
an empty shell, it was a big wreck,
and so this is sort of not a good example.
And, in fact, even to this day,
some of the empty shells
of this 19th century factory
are still sitting there, a few blocks
from where I grew up.
So, this is not a good example
of moving on.
I want to give you another example
of, again, not computers,
but another industry
where we've done better,
or you can judge after I've given you
the little story.
So, here's another nice picture,
-- nice --?
It's a picture of
an impressive, big industrial complex.
Now, the thing that's
interesting about this perhaps
is that you just walked
right past it this afternoon.
It is in fact the Orange Nassau 1 mine,
which was right at the train station,
here, where you got off, this afternoon.
There's still one tiny bit of it,
but, of course, you didn't see it,
you mostly didn't see it,
you didn't see any giant wreck either.
And in this case, change was accepted
and in fact, in this case, it was
the conscious action of the Dutch state,
that said this is the wrong way to do it.
It's brilliant and it's impressive
and it's driven our economy,
but we have to change,
it's the wrong way to do this work.
And, in fact, it's a famous event
in local history,
right here in this building,
on the stage here in the Sauberg,
that the Minister of State came and
announced, "We are closing the mines."
And within 10 years, after 1965,
it was done.
So now, of course, coal mining
has not ended,
and hasn't even ended in our Eutropolis,
and so if you go off to the edge
of our Eutropolis in Hambach,
you see the way coal mining
is really still done today,
and it's radically different from,
you know, digging a dark hole,
crawling under ground and
heroically chipping away at rocks.
It's done by these giant machines --
whoops, sorry, I have the instinct to use
a pointer, which I shouldn't --
which are sort of the size of
this whole theater building,
digging away, you know,
these monsters are constantly
digging up the electricity we need
for doing our gadgets and so forth.
So, let's move on to computers.
So, I want to begin...
I slurred my home city,
so, I want to make it up
to Philadelphia a little bit,
by coming back to another
point of history.
At the time that the Brill factory
was about closed,
there were some very bright
electrical scientists
and physicists and engineers
at the University in Philadelphia,
just a few kilometers
from where I grew up,
and they invented something new,
so, they invented a computer --
you may know that before, say the 1940s,
a computer meant a person
who was good at, you know, dashing off
figures on pieces of paper.
So, what they realized was,
you could do that with electrical devices,
and so the ENIAC
was the first all-electronic,
automatic computing device.
It used as its basic elements
vacuum tubes --
and if you're as old as me, but maybe not
if you're much younger than me,
you don't even have
this experience of looking
in the back of an old television set
and seeing these glowing glass balls --
and those were racks and racks
of these glass balls.
These vacuum tubes were the things that
were used to make this computer function.
Now, this computer was developed
under the pressure of war,
and it is said that it was finished
just in time to have no role whatsoever
in World War II.
But it still did calculations
for the military,
it did solve physics problems you know,
artillery shell -- pssh ---
you know it did computations
about how those would work
and it did function for a few years.
But, of course, it was superseded.
And then its successor was superseded.
And the computer industry is an example
of a succession of innovations
of physicists, engineers, understanding
new ways of doing things,
putting them into practice
and wiping out what existed before.
So that we've come,
by now we've come to --
Of course, computers are everywhere,
big and small,
they're everything, so I'll choose
to illustrate with the big,
you know, we still have big,
room-size machines.
This is one out at
the Juelich Forschungszentrum,
actually just a few kilometers
from where the giant hole
in the ground is, the big mine.
So, this is not, you know, mining coal,
it's sort of mining knowledge.
Out of what? Well, out of electrons.
It still functions according to
the same principles as the ENIAC
except way, way, way smaller,
that is all the devices that used to be
the size of vacuum tubes
are now shrunk down to
smaller than the size of a hair.
So that, you know, the functioning
of the ENIAC
is all shrunken down to about
a millimeter of this machine.
And its overall capability
is something mind boggling.
This particular machine is not used
to maintain Internet databases,
it's used for scientific purposes, for
simulating the action of the human brain
and for understanding other kinds
of physics problems.
It seems like physics always is somehow
at the cutting edge
of how to make, you know, the best
and the next machine.
So, I'm going to move on and tell you now
about quantum computers,
so, my subject, and how it has
the possibility of making machines
that are as far beyond Jugene,
this IBM supercomputer at Juelich,
as you Jugene was compared with ENIAC.
But we're actually taking a new turn
that we haven't taken over these 50 years,
which is to go back and examine
and try to break
the rules at the very basic level,
at the level that the basic switches
of the computer work.
So, here's a few technical pictures...
just to say... how do computers work?
Well, they work by knowing
how to do 1+1=2,
and doing it very, very, very much.
So, it does that with these things
which are referred to as logic gates,
AND's and OR's and so forth.
And if you ask: Well,
what's an AND or an OR?
it's some kind of electric circuit.
So, here's a little sketch of one,
and it has some resistors and diodes
and things which are called transistors,
these cubes.
So, the reason I, you know,
reach down to this
is that this, say the transistor,
the thing which, in some sense,
has remained functionally invariant,
from the time of the vacuum tubes
to the time of the little tiny things
on computer chips,
is something we're going to change.
We're going to change the basic rules
about how they work.
So, let me talk for a moment
about how they work.
So, what is a transistor?
It's something which is a controller,
it's a switch,
it's something that can turn on and off.
What is it turning on and off?
Well, for all those years,
as all those new generations
of computers were discovered,
it was involved in the turning on and off
of an electric current.
So, electric current goes from
one place to another
called the source and the drain.
This is a photograph,
a microscopic photograph,
of how a transistor more or less
looks in the present time.
It's a very tiny structure etched onto
or grown onto a surface of a crystal.
And so the current goes through some
little obstacle course of barriers,
and gets to the other side.
And the way it works is by --
the controlling of that current is by
the thing called a gate.
So, there's a way of turning
on and off the flow,
which is accomplished itself
by an electric means,
by turning on and off an electric voltage.
So, that has remained invariant,
that is the starting point
of building up gates, and 1+1=2,
and stock market modeling,
and video games, and everything,
is built up on the functioning
of these kind of devices.
But we're going to change the rules
of how they work.
I can describe it in terms of this,
by saying here's a way
of changing the rules.
This is always based on
the flow of current,
So, we're going to stop
the flow of current,
we're going to not have any current
ever flowing through this structure,
but we'll use something else
to contain information,
to save information, store information.
When we bring it to a halt,
it becomes more evident
that this current is actually composed
of individual elementary particles
passing, so to speak, one by one,
through the transistors.
So, we'll bring them to a halt,
and we'll have individual electrons stuck
at specific points inside this transistor.
Now, an ordinary transistor wouldn't work
at all anymore if you did that.
But the point is that we're going
to use now even different rules
for what really processes the information,
what contains the information,
that we're going to use to represent data,
represent calculations.
It turns out that what we will use,
or a promising thing to use,
is a specific attribute of electrons;
the fact that they spin on their axis.
So, they're charged and
they spin on their axis.
The spinning produces a magnetic field,
so it produces a tiny little magnet
associated with each electron,
and the magnet being up or down
is like the 0 and the 1 of a computer.
Except that the magnetic direction
can be anything,
so it's a little bit more than just a bit.
And it begins to have attributes
which we can only describe
using the laws of quantum physics
rather than classical physics.
Now I'm going to say a few words
that even I think our are going to be
challenging for some of the audience,
but stay with me a little bit.
So, we're going to talk about how two
of these electrons can be correlated.
Suppose you push the green electron
and you push it right on top
of the red electron.
It turns out that the nature of electrons
is such that these two spins
like to anti-align.
They will preferentially anti-align.
If one is up, one is down.
But up can mean anything,
up can mean any direction in space.
But they have the peculiar correlation:
If one is up this way,
the other one is guaranteed
to be down the other direction.
And that turns out to be
a form of correlation
between two elementary objects,
between two bits,
that is beyond any kind of correlation
that we can have in classical systems,
and it's the thing which is referred to
as quantum entanglement.
Now, I'm not going to say
that this is easy.
In fact, it's exactly the thing that
Albert Einstein in thinking about said,
"This is spooky,
this is weird, this is crazy."
But in fact we've gotten --
we live with it.
I mean, we live with the spookiness
and we don't think of it as spooky at all,
in the sense that it obeys clear laws,
it behaves in predictable ways
and we even understand that once
you've made things that are entangled,
you can pull them apart and
separate them by long distances
and they can remain entangled.
And this sort of pulling apart
and then interacting with
other electrons is the basis
of how you program a quantum computer.
Now, as I say, that doesn't
really tell you
that much about a quantum computer,
but I'll try to give you some idea
of where we are on this enterprise.
We understand that this is possible,
we understand that it will
speed up calculations,
initially kind of physics
and mathematics calculations,
but what next I have no idea,
whether we'll have the sort of
quantum tablet or something.
What I can tell you is that there is
real current progress in the laboratory
in actually making this a reality,
but it all looks sort of
radically weird and different
from any existing computer hardware.
So, people have been able to put
a few qubits onto a chip,
and the chip can be mounted
into a structure
and put into, quote, "a computer".
Although the main thing that
this so-called computer on the right is,
is something that keeps noise and
disturbances away from these qubits,
because they're extraordinarily delicate,
they're extraordinarily sensitive
to noise in the environment.
So, this is really a refrigerator
with a lot of shielding.
Now, I might say a little bit about:
What is my role in all this?
I'm a theoretical physicist, I like
to think about how all this works
and I've tried to indicate
what has to be improved
in order for this to finally fully work.
So, this is a very technical little slide,
but what its message is, is that
we've been able to understand
how to measure qubits to tell
how well they're working,
and over the last 10 years
their basic functioning
has improved by about a million.
It's actually measured by
how sensitive they are,
or how well protected they are from noise.
So, improvements of 10^6
usually make for some differences,
and in fact it has enabled the possibility
of assembling large machines.
and trying to test them out.
It has been about 10 years
to get to this point,
and I predict we're sort of halfway there,
from the sort of starting point
of having hardly anything
to where we are now,
and then another 10,
something like that, years,
we'll really start having
functioning devices.
So, I've also played the role
of just saying --
this is all very sketchy at the moment.
These chips only have a few qubits,
so, I've introduced ideas for, you know,
what is in fact the structures
that one should grow on to chips to make
multiple qubits, a multitude of qubits,
So, these sort of
aesthetically pleasing structures
also are sort of engineering diagrams
for future machines.
I did this for many years as
a researcher in the United States,
working for IBM Research,
but in the last few years,
I've come here to this region,
and I live right here in Heerlen,
and I work at the Aachen University,
and, in fact, Aachen, which, of course,
began 150 years ago
as a place where mine engineers
were trained,
is now open to having someone like me come
and work on the strange subject
of quantum information.
So, this last picture shows --
I try to convey what I really do.
What do I really do? Of course, I really
answer emails and things like that,
but, actually, what I really do is,
in trying to teach
other new researchers,
young researchers, how to do
the work I do,
I'm having them --
you know, in conjunction with me --
they try to work things out.
Physics always, of course,
gets down to equations,
you have to calculate things
and model things,
and so my role is to have
my young workers work things out
and to have the taste to perceive,
but, yes, this stuff on the left
which looks very scribbly
and not very nice, is really brilliant,
and this is actually not so smart.
Thank you very much.
(Applause)
