Transcriber: Andru Shively Reviewer: David DeRuwe
Tim Leonhardt: Hey, Sergey. Sergey Bespalov: Hey, Tim.
TL: Some people think quantum computing is hard.
SB: Of course, man, I mean, it’s physics.
And even worse, man, it’s quantum physics.
TL: But, Sergey, if we don’t understand or use quantum physics,
we can't build quantum computers.
If we can't build quantum computers,
there’s a heap of hard problems that we’ll never solve.
But we want to, we need to,
and it will be really, really hard to do it without.
It’s a little bit like telling Margaret Hamilton,
the software engineer for the Apollo Moon Lander,
to do her coding job without the digital computer.
So how are we going to do this?
SB: Hey, man, relax. I mean, we’re switching too fast here.
But relax, we’ll get there, and we’ll, in the future,
pioneer this weird field you were just talking about.
TL: It’s called Hilbert space.
Yeah, so my name is Timothy Leonhardt.
SB: And I’m Sergey Bespalov.
TL: And in a universe far, far away and a time long, long ago,
we were on the way to the fields of purity and science and brightness.
SB: But we joined the dark forces. (Muffled laughter)
Because we left the fields of purity, right?
And now we’re doing distributed ledger technology, artificial intelligence -
and for some reason it doesn’t switch now, yeah -
extended reality and quantum computing.
Let’s start with the fundamentals, Tim.
TL: Exactly. Let’s start with the fundamentals.
Always love to talk about that. And we go one further.
So, what does quantum computing involve? Typically, we have to start with physics.
And I’ll try to be quick.
There are essentially new laws you have to learn
and that you can always also use as a tool to use with new computers.
So what are these new strange rules?
One is superposition. And you remember the coin toss, yeah?
Typically the outcome’s 1 or 0.
In quantum computing, it’s a little bit like the coin
is turning the whole time,
and you can change the mixture of heads and tails gradually, as you like.
So it’s a little bit of parallelism, but it’s also not.
The other thing is tunnel effect.
(Laughter)
Imagine that typically you have a barrier that you’re running into,
and you can’t cross.
Now, with quantum computing you have some strange effects -
you throw a squash ball against this wall very, very hard and very often,
and suddenly it morphs and poof,
and you’re on the outside in a new territory that you can explore.
And the last one, yeah, that one even I tried and found a little bit confusing
because it's called entanglement.
So, imagine you have two of the dice that you just saw presented before,
and you play against your friend and you want to have doubles always.
Funny thing is, you won’t get it, yeah.
We all know you can’t really change that.
With quantum physics, actually,
you can entangle them and every time you throw them,
you won’t know which doubles you get, but it will be 100% sure to be doubles.
And, funny thing is, you can do this on the different sides of the universe,
and you will always get the same result.
So, there you go.
SB: Tim, but what are you talking about here, actually, I mean ...
TL: Quantum physics, of course.
SB: Oh, I got it, I got it - this is the thing where you just kind of,
you guys take a cat and then put it in a box ...
TL: Wait. No cats hurt, no boxes involved. It’s just a thought experiment.
SB: Of course, of course. You guys, theoretical quantum physicists,
you just do thought experiments.
You never produce something, you know, real that we can actually use.
TL: Actually, not. We have a new application.
SB: So, you’ve finally built the box and put a cat in it?
TL: No, we built a box and put a computer in it, a quantum one.
That’s how it looks.
Well, of course, with all of this, this is on an IBM system,
and the interesting thing is that every one of you in the room
So, it’s really available to everyone on the small scale,
and there are a lot of startups building these
and bigger corporates that start to scale up this technology,
and I, as a physicist, I love it because it’s a technology push,
a new technology that might change something in the society in the future.
SB: But wait, Tim, isn’t this just
a typical hammer and you’re looking for a nail problem, right?
So I mean, where is the real-life application?
We need some real-life application because only this creates innovation,
by so-called “market pull,” right?
TL: So, where’s your market pull?
SB: Well, OK, let me show you. Back in the days ...
I will try to tell you a story about two chemists.
By the way, where’s the guy, two man chemists, Carl Bosch and Fritz Haber.
They developed this Haber-Bosch process to basically take ammonia from air
and create a - no, not ammonia. TL: Nitrogen-based.
SB: They took nitrogen, created ammonia and produced fertilizer to feed the world.
Groundbreaking, huh? Huh?
TL: How do you do it?
SB: Well, simple.
So basically, we take the natural gas, all right,
remove sulfur from it,
then put water in the primary reformer, and then we heat it up slightly.
TL: Slightly? You mean like the room temperature?
So like, the bacteria can do this, the exact same thing at room temperature?
(Laughter)
SB: Well, not quite - a couple degrees hotter.
TL: Seems like you’re joining the dark forces.
SB: Yeah, man. We use about 2% of the world energy produced
only for this one. Mmm?
Man, this is super cool, but it’s not that environmentally friendly, right?
So, basically, we have a problem,
and I would like to join the good forces again, but we have a problem, right,
and I would like to show you where the problem is.
So basically, we would like to understand how the nature does this,
but in order to understand this, we need to simulate many things, right?
And we need some approaches to do that,
so basically, on one hand,
we have this kind of a molecular mechanics approach where we treat
the molecules as, well, as classical, physical objects with the balls and -
TL: Cool, easy enough.
SB: Yeah, yeah, but unfortunately we don’t get the accuracy we need
and basically we can just simulate the geometry optimization,
but we need to simulate interactions between the molecules,
and we need to simulate their polarity and everything,
but for that, we need to go to the quantum mechanics, right?
Another approach is doing semi-empirical, where we just measure
a couple of things in the lab, put it in the computer,
then calculate and -
TL: It looks good.
SB: Not quite. The problem with that is, I mean,
this is already like a hundred times slower than that one.
And you see how long it takes, right? And, it’s not accurate enough, right?
So what we would like to do is, like, we do this Ab initio method.
It means from the beginning we would like to take the equation
from that evil guy with the cat -
TL: Schrödinger. SB: Yeah. TL: No. SB: Okay, sorry, not evil guy. Good guy. -
and to calculate this,
but for huge molecules, it seems to be an intractable problem
because if it’s, well, it will take too long to do this.
It’s not possible.
Can you help me?
TL: I think so. There are a couple of very good ideas.
Even Richard Feynman, I think, almost thirty years ago said:
“Nature isn’t classical, dammit.”
But if you want to simulate nature, make it quantum.
So, that’s what we are trying with quantum computers.
You see, you just start from the classical world.
It’s a little bit like in software code.
You have a couple of bits, this is qubits, on the left side, you start with them.
You do all these nice operations and move through the barriers,
move the waves in the way that you know is right.
It’s a little bit hard, but at the end,
you have one solution and one block that pops up that you can measure.
So that could work.
SB: Well, I mean, this sounds awesome, Tim,
but do you think there are some areas,
maybe other areas than chemistry that the quantum computers might help us?
TL: Yeah, there are a couple of theorists who really thought about new ideas,
how to improve machine learning.
They have very specific problems that they’re speeding up.
There’s this simulation idea
of not only simulating molecules but major financial systems.
There’s optimization problems of how you do scheduling far out, for instance,
for this room at RWTH.
Very hard, I heard. And there’s the security problem.
We have Shor’s algorithm, and in ten years, roughly,
it will really be an issue that quantum computers might crack our communication
and make data insecure. So, it’s relevant.
SB: This sounds exciting man, but come on.
I heard this whole thing isn’t practical. I mean, it’s not working.
TL: Yeah, that’s where we have kind of problems.
So if you ask Google how the protocol type is coming along ...
it tells you this.
So, quantum computers are somehow in this position of being very successful,
and at the same time, not working at all.
SB: Can I check that? TL: That’s a tricky question.
But maybe I can tell you how it’s going on.
So, actually, what I’ve been doing to check if quantum computers are faster -
The original algorithms of Shor, like if you look at them,
how many qubits you need, and then how many operations you have to do,
it’s just unfeasible.
They didn’t take into account that these machines
that experimentalists had to build are small and erroneous.
So they're trying something else.
And maybe you know this Galton board,
where you throw a ball in the top and then it goes left or right at the pit,
and what comes out is really nice bell shape
that even the chemists and mathematicians laugh,
because it pops up everywhere.
Some of these distributions are really hard to produce,
but you need them for all kinds of calculations.
So what we can do with a quantum computer
is we can take the samples of throw the balls very, very quickly,
and the interesting thing is that Google and Xanadu have built machines
that do this on microsecond scale,
and supercomputers take years to do this job,
and so we have quantum advantage, but...
SB: Yeah, listen, this sounds interesting, and I mean,
this explains some theoretical, abstract algorithms, selling something,
but, are there some, like, real-life applications, right?
TL: Yeah, that’s where we’re getting back to your nitrogen fixation.
I mean, physicists have heard that this is a hard problem,
and about five years ago, they started to publish papers on this.
They alreadly calculated how many qubits I need,
what kind of gate operations I need to do, and they came out with great numbers.
You only need a million to 100 million qubits. Bummer.
But it went on, and they did new results.
They involved all this stuff that already existed, like this UCCSD-something.
So then actually, they reduced the number of qubits
and they’re really developing the results fast.
The interesting thing is they even run this on new quantum computers.
It’s more than a theory.
You really do your nitrogen and some diamond calculations
on a real quantum computer, and it works.
It’s not faster than the supercomputers, but we’re getting there.
SB: But, Tim, listen. I mean, all good, but those guys are all cracks, you know?
And I mean, they’re specialized in their field and nobody understands them, but ...
Can we get with those scientific cracks?
TL: Yeah. I mean, so on one hand, look at the paper. It’s from 2017.
So if you are studying math or physics,
you can catch up in a couple of years just doing the tasks, reading the papers,
and you can try it.
And for everyone else here in the room, I mean,
some of the most interesting innovations
for applications that really changed our life, out-of-the-box thinking -
SB: Please, leave the cats alone, huh? TL: Yes. Never, never hurt. -
Some of this didn’t happen at universities.
SB: Yeah, this sounds good. TL: Give it a try.
SB: I mean, this sounds good, but can you tell me how can I join the team too,
to develop the future of quantum computing and to become a quantum data scientist?
TL: And you don’t have to go into a rapture for it,
just take your cell phones out, and there are many possibilities.
There are a couple of papers on how industry might use this,
how in these cases are kind of screens.
SB: By the way, I asked this for a friend of mine. Not from me.
Just so we’re clear.
TL: You can read these magazines, you can go to “Qiskit Textbook.”
It introduces these gates,
but if you really want to make something fun with it, that’s here,
you can do art, you can do Lego quantum computers.
There are people building games on this stuff.
So, really think about what can you do with it. And there are many courses.
If you want to go deeper into the physics, feel free to join.
We need people to work on this. It will be our generation that shapes how it looks.
SB: So we really hope that you now share
the joy that we have with working with quantum computers.
TL: We really do hope if you take one message away from this.
SB: As a good friend of ours Obi-Wan Kenobi said:
“Don’t ask quantum mechanics what it can do for you;
ask what you can do with quantum mechanics.”
TL: Thank you. SB: Thank you very much.
(Applause)
Maybe one more message before you continue.
Another great thing to do is to join the team of tactics of RWTH.
I was part of it ten years ago,
and there’s nothing better to see what it has become.
And you can be the person who shapes it for the next.
(Applause)