Transcript

From bit to qubit: a quantum symphony in today's computers | Catalina Oana Curceanu | TEDxRoma

Translator: Michele Gianella
Reviewer: Denise RQ Thank you. Good morning everybody! (Applause) We have just listened in music what we want to do in computer science: the transition from the traditional
to the quantum computer, from bit to qubit
in tomorrow's technology. Such technology should exploit
quantum mechanics, behaviors that although bizarre - and behind me, in this image, we have a really strange behavior - if instead of the two skiers behind me, there were some electrons, these behaviors actually do happen. So it's like, from the weird world
of quantum mechanics to tomorrow's quantum computer. In order to appreciate the innovation
a quantum computer would represent, let's start from our current ones, from the current technological limits
yet to be overcome. Even today's computer saw the light thanks to a breakthrough,
the invention of the transistor, made by the three researchers we see in the photo behind me, Shockley, Bardeen, and Brattain, all Nobel Prize recipients,
60 years ago now, for the invention of the transistor, another brainchild of quantum mechanics, based as it is on the discovery
of the atomic structure. The transistor -- a fundamental unit
of all our modern technology. All microprocessors contain
a huge number of transistors. Think about this:
should all of us, in this room, put all our technology together, we have more than a trillion transistors, all packed together
on these microprocessors: a staggering figure. How far can we get to? How far can we increase
the computing power? Clearly it all depends on how long
we can keep shrinking transistors. Here we have instead the curve, the so-called Moore's law according to which transistors' number
doubles approximately every 18 months. Will there be a moment however when this surge in the number
of transistors hits a limit? Certainly yes: a wall will be hit when we get to the limit
of the atomic scale. We can't imagine to make
a transistor smaller than an atom. So what will we do then? Shall we settle down with our technology? No. Instead, we'll take advantage
of quantum mechanics' quirks, not as a limit but as a huge opportunity, as a resource
that will allow us to go further. Quantum mechanics, this institution of modern physics - here's one of the most famous meetings, you'll certainly recognize
some of them in this photo - which describes the behavior of particles, atoms, but also molecules, So it depicts the structure of the atom through the breakthrough
of the wave function, which describes the behavior
of atomic systems - thus on a very small scale. Which quantum mechanics behaviors would we like to use
in tomorrow's computers? The first and foremost is the so-called quantum superposition: the wave function can be - and actually is,
for microscopic systems - the sum of all behaviors. Atomic systems are
in several states at once, in all states allowed
by quantum mechanics. So if an electron can either
go right or left, in quantum mechanics, it will go both right and left
at the same time. The second quirk in quantum mechanics is the well known "Entanglement," namely an intertwining between the particles that either
were born together or have interacted. If for example we take
two particles, called Alice and Bob, who are in an entangled state, even if we place them far apart, if something happens to Bob,
Alice will be instantly affected. To use a rather romantic metaphor, it is like for two lovers, they are also, somewhat,
in an entangled state. These properties made Niels Bohr, one the founding fathers
of quantum mechanics, say about this theory
- and how couldn't we agree. Those who aren't shocked
by quantum mechanics cannot possibly have understood it. So, starting from these two milestones, superposition and entanglement, Richard Feynman and David Deutsch,
portrayed in these pictures, have proposed the creation
of a new type of computer which is conceptually
very different than current ones. How different would this computer be? Current computers work by processing the so-called bits, a stream of 0 and 1 which ultimately return final results via algorithms. In quantum mechanics instead, by using the superposition of states, we can use 0 and 1 simultaneously. This would clearly trigger an exponential increase
in the computational power. And consequently, much faster
and much more powerful computers. Bit 0 -- (Piano music) Let me show you
how the switch would feel like. Bit 1 -- (Piano music) The Qubit, instead -- (Piano music) Really amazing. Ladies, wouldn't it be... (Applause) It'd be so cool
if we ladies could sometimes be in an entangled state
and do more things at once. But we are too big:
billions of atoms together who don't keep the state
of quantum superposition. So, if it's a bowl of cherry,
where is this quantum computer? Why don't we have it yet? Because it is very hard
to generate superposition states, and it's even harder to preserve it, And that's what we are trying to do. Let's look at the enemy. The goal is a quantum symphony -- (Piano music) But if something interrupts the pianist, for example, he checks his phone. What happens? It loses coherence, the qubit disappears,
the system doesn't work any longer. So decoherence is our enemy, and it often shows up. It destroys the Qubit, so the entangled state,
the entangled behavior, the quantum superposition state
we wanted to work on is no more. It's vanished, gone away. Studies are made
in many labs around the world to keep the qubit, create it and keep it alive. Even the group I have the pleasure and duty
to coordinate in an experiment in the laboratories of Gran Sasso,
under the mountain, in this wonderful lab
connecting l'Aquila and Teramo, we are trying, on atomic
and nuclear systems, to work on quantum superposition
and to find limits or conditions that will allow
future quantum technologies to be more accessible than they are now. Some prototypes of quantum computer
are already in place, you can see them in these images. Sure, they're very complex,
the size of a wardrobe. But let's not forget
that even our computers were that bulky, many years ago. This gives us hope
that tomorrow's quantum technologies will allow us to make
this incredible computer. What will it do then? 20 years from now, we think this computer will give us quantum cryptography
and a real cyber security. Information thieves, hackers,
will have a much harder time: the moment they sniff the traffic,
they're detected, because they destroy
the quantum coherence. They will be useful to study chemistry, molecular systems
in biology and in medicine; and even to study the human brain, this extraordinary structure made of billions and billions of neurons. Last but not least, in a globalized world
they'll do a much better job at handling big data: we live with big data
and quantum computers will help us solve and analyze
more quickly these big data. So, to wrap up, I just point out
that quantum technologies and the passage through a quantum symphony from the bit generation (Piano music) to the Qubit generation (Piano music) will change our world. It's amazing, it's challenging,
but it's also fun. So let's do it. Thanks to... (Applause) Many thanks to Venceslao Marinaro. Thanks. (Applause)