[AUDIO LOGO]
JAMES MANYIKA: Well, maybe let's talk here.
What is quantum computing as distinct
from classical computing, and why does it even matter?
HARTMUT NEVEN: So maybe a good place
to start with is to realize as powerful as computers
have become, there is a list--
actually, a long list of problems they cannot solve
and actually will never solve.
So quantum computers are a new computational modality
that can complement what traditional computers can do.
And that will help us in--
computations, I would think, really matter,
like simulation of physical systems.
It can help with solving optimization problems or key
challenges in machine learning.
JAMES MANYIKA: But give me an example of something
that shows the distinction of what a classic computer would
do versus what a quantum computer would do.
HARTMUT NEVEN: Try something-- so we are a search company,
so let's discuss a search problem.
And computer scientists say that the simplest search problem
we can think of is unstructured search, where
you pick one item out of N.
So let's envision it in the following way.
Imagine a huge closet with a million drawers,
and I take an item and I put it into one of those drawers.
So your task is to find the item.
So how many drawers will you have to open
or how many algorithmic steps does that require?
JAMES MANYIKA: Well, I'm going to go with an average--
so I imagine probably at least half a million
if you've got a stack of million things.
So I'd imagine half a million.
HARTMUT NEVEN: Exactly.
So an average, if it's random-- if I place this item somewhere,
sometimes I get lucky and open the first drawer and I find it.
And sometimes, I'm unlucky and I have
to open one million drawers.
On average, exactly right--
it's half a million.
But as amazing as this may sound--
I like to call this a quantum [INAUDIBLE]---- if you had--
if this closet would be a quantum closet--
or let's make it more realistic, if it
would be a quantum memory--
then you could find this item with certainty
with only 1,000 steps, so only the square root of 1 million.
JAMES MANYIKA: Whoa.
People in the audience are probably wondering--
so how is that possible in this world to go from--
I had predicted half a million to now 1,000?
How in this world is that possible?
HARTMUT NEVEN: Exactly.
So yeah, how in this world is this possible?
And the answer is, it's not possible in this world.
This was not a trick question.
But one key lesson from quantum physics
is that there is not just this one
world we experience right now, and rather suggests
that there are many, many parallel worlds,
and that we live in a multiverse and that every object is really
a multiobject.
So somewhat esoterically speaking,
you could say quantum computing is the first technology that
takes this idea serious, and it farms out computation
into some of those parallel worlds
as well to obtain the answer quicker.
JAMES MANYIKA: Well, why don't you try with an example?
Give an example of how--
so we can fully envision this.
HARTMUT NEVEN: So yeah--
I know this sounded a little bit like I'm a philosopher.
I apologize.
[LAUGHTER]
JAMES MANYIKA: No, yeah, because when
you talk about multiverses, it's very philosophical.
But I'm trying to think is there a practical way you could
illustrate what you mean about these quantum
states in multiple spaces you're talking about?
HARTMUT NEVEN: So for our project, of course--
various things we want to achieve,
but if I could only get one thing right,
it would be the following.
My wife and I, we have two boys as children,
and I want them to enjoy the world as much as you and I had
the opportunity to do.
And in order to ensure this, we have
to slow down climate change.
We have to develop an energy economy that emits less CO2.
So we need to find new ways to produce energy, transport
energy, and store energy.
And if we had a quantum computer,
it would be a marvelous tool to design
the technologies needed here.
And of course, I'm aware we are racing the time.
We need to build this machine and then
give it to the engineers to do the other work.
JAMES MANYIKA: So that's an example
of what you might call a quantum advantage kind of problem
that these quantum computers can help us solve.
But tell us what is it going to take
to actually build these systems and build these quantum
computers?
What are the key things we have to get right?
I mean, you've been working on this for a while now.
HARTMUT NEVEN: So I know some of you
will have the opportunity to see actually the quantum AI
labs down the street, and you can see the status
where we are.
So the mission of our team is to build a large useful quantum
computer with about a million physical qubits.
So today, we have 100 qubits, so there is some ways to go,
but we hope to get there by the end of this decade.
JAMES MANYIKA: What's a qubit?
Explain that.
HARTMUT NEVEN: So a qubit--
if you'll allow me before answering this,
I think one message I would like the audience to take home is--
because you often read a little bit otherwise in the media--
our team at this stage is very confident
that we will build a large quantum computer.
So sometimes there's still questions
whether that's even possible.
JAMES MANYIKA: Right, but why don't you
explain what a qubit is, and then I'd
like to come back to this question.
So what are the progress you and your team
are making, just to help us understand?
HARTMUT NEVEN: So a qubit--
let me try two metaphors to not make it too metaphorically.
So if you are very simple-minded,
it describes the world in single bits, so black or white.
If you're a little bit more sophisticated, you realize,
oh, wait, there are shades of gray in between.
And if you're a quantum computing person,
you put black and white on the poles of a globe--
of a sphere--
and you realize, oh, all intermediate states
between black and white are actually states on this sphere.
And so this is one metaphor.
Let me try another one.
Often, when you read about qubits in newspapers,
they say, oh, qubit can be in 0 or 1 or black and white--
it's the same moment.
And people scratch their head-- how is that possible?
I think it's easier to understand
if you consider a few bits.
So let's-- what I often like to do is I pull out a few coins,
throw them on the table, and then say, oh, look,
there's one classical configuration--
let's say heads, heads, heads.
But again, quantum mechanics would tell us
if you want to properly describe it,
even though it's imperceptible to us,
the other configurations--
in this case, would be eight other configurations
with three coins--
JAMES MANYIKA: So 2 to the power of 3 for the three coins.
HARTMUT NEVEN: Exactly.
It would be 2 to the power of 3.
And you have to consider all these configurations in order
to properly describe the system.
And here, you get also with the exponential power
of supercomputers-- sorry, quantum computers comes from.
If you had a fourth coin, it would already
be 16 possible configurations.
And if you have n qubits, it would
be 2 to the n configurations, which tends
to be huge exponential numbers.
And all those states can be processed in a single time
step inside a quantum computer.
JAMES MANYIKA: That's very cool.
So you're-- I mean, this year has been a fascinating year
when it comes to quantum computing.
I think one of the Nobel Prizes actually
went to the three scientists who did work
on quantum entanglement.
One of the things that often comes up
with quantum computing, Hartmut, is the concerns
that people have about a whole range of things.
I mean, some people in the room may know,
for example, Shor's algorithm.
So this is an algorithm that was actually
devised in the '90s by a scientist called Shor, which
basically suggested that if you could have a quantum computer,
you could actually do what's called
prime number factorization.
And a lot of our encryption systems
rely based on our ability to make it--
that it's very, very difficult for a classic computer
to actually factorize prime numbers.
But he showed that if you had a quantum computer,
you could actually do that.
So one of the concerns that people have is,
in fact, will this mess up all our encryption,
security, privacy systems?
So from a responsible innovation standpoint,
how are you thinking about that question--
those kinds of questions that people may have either concerns
or worries about?
HARTMUT NEVEN: So there is some good news
in the sense that computer scientists at governments,
academia, and companies have--
they're quite aware of the problem you described,
and they have been busy developing
encryption protocols that are immune to quantum attacks.
So once we have the big use for quantum computer,
encryption by that time will change.
Our data will still be safe.
Actually, the National Institute of Standards and Technology
this summer, they published four suggested protocols
to keep data safe in the age of quantum computers.
JAMES MANYIKA: Right, but you're also thinking about other
aspects of being responsible and, in fact, including--
because questions about jobs and inclusivity--
say more about what you're thinking about with regards
to those other aspects of being responsible?
HARTMUT NEVEN: One key aspect for our field
is workforce development.
So in some ways, it's good.
Quantum technology is not just quantum computing,
but quantum technologies overall are a job creator.
And we create more jobs than we can currently fill,
and that's also true for our team at Google.
And in quantum computing, similar to many other STEM
fields, there's still a lack of diversity,
let's say, along gender or other dimensions of diversity.
And of course, we would like to improve on this.
And that's maybe a little call to action to the audience.
So if you have a young student in your vicinity,
maybe point them to quantum information science
as an interesting career path to take.
JAMES MANYIKA: So at the start of this conversation,
Hartmut had described this as the fast-approaching future.
So do you have a view of when we can expect fully
functional quantum computers?
HARTMUT NEVEN: So our plan right now calls
for finishing this by the end of this decade
when we will be able to handle commercial workloads.
Again, interesting discoveries already made today,
but to have a solid quantum computing service
that third-parties can access will be done, I hope,
before this decade ends.
JAMES MANYIKA: Well, I tried to talk Hartmut
into giving us a demo, but he said, no-- in fact,
what we'll do instead is we'll do a field trip.
So I think some of you signed up to do a field trip to his lab
to actually see some of what he's building.
So hopefully, we'll do that later this afternoon and some
of you will join us for that.
But this is fascinating, Hartmut.
And every time I have a conversation with you,
I'm reminded of-- you mentioned Richard Feynman.
I mean, Richard Feynman in his famous quote
when he said something along the lines
of, if you think you understand quantum computing,
you don't understand quantum computing.
And I always end up feeling that way, but thank you.
[LAUGHTER]
[APPLAUSE]
HARTMUT NEVEN: Thank you.