Depending on who you ask, some say quantum computers could either break the internet, rendering just about every data security protocol obsolete, or allow us to calculate our way out of the climate crisis.

These super-powerful devices, an emerging technology that exploits the properties of quantum mechanics, are causing a stir.

Just last month, IBM unveiled its latest quantum computer, Osprey, a new 433-qubit processor three times more powerful than its 2021-built predecessor.

But what is all this hype about?

Quantum is a field of science that studies the physical properties of nature at the scale of atoms and subatomic particles.

Proponents of quantum technology say such machines could usher in rapid advances in areas such as drug discovery and materials science – a prospect that holds out the tantalizing possibility of creating, for example, batteries or materials for lighter and more efficient electric vehicles that could facilitate efficient CO2 capture.

With the climate crisis looming, and technology with the hope of solving complex problems like these are sure to generate a lot of interest.

It’s no wonder, then, that some of the biggest tech companies in the world – Google, Microsoft, Amazon and, of course, IBM to name a few – are investing heavily in it and looking to take their place in the future. quantum.

## How do quantum computers work?

Since these utopian-sounding machines attract such frenzied interest, it might be useful to understand how they work and what differentiates them from mainstream computing.

Take all the devices we have today – from smartphones in our pockets to our most powerful supercomputers. These work and have always worked on the same principle of binary code.

Essentially, our computer chips use tiny transistors that work like on/off switches to give two possible values, 0 or 1, otherwise known as bits, short for binary digits.

These bits can be configured into larger and more complex units, essentially long strings of 0s and 1s encoded with data commands that tell the computer what to do: display video; view a Facebook post; play an mp3; let you type an email, and so on.

But a quantum computer?

These machines work in a totally different way. Instead of bits in a classical computer, the basic unit of information in quantum computing is something called a quantum bit, or qubit. They are usually subatomic particles like photons or electrons.

The key to a quantum machine’s advanced computing power lies in its ability to manipulate these qubits.

“A qubit is a two-level quantum system that allows you to store quantum information,” Ivano Tarvenelli, the world leader in advanced algorithms for quantum simulations at IBM Research Lab Zurich, told Euronews Next.

“Instead of just having the two levels zero and one that you would have here in a classical computation, we can construct a superposition of these two states,” he added.

## Overlay

Superposition in qubits means that unlike a binary system with its two possible values, 0 or 1, a qubit in superposition can be 0 or 1 or 0 and 1 at the same time.

And if you can’t figure that out, the analogy often given is that of a penny.

When standing still, a penny has two sides, heads or tails. But if you return it? Or spin it? In a way, it’s both heads and tails until it lands and you can measure it.

And for computing, this ability to be in multiple states at the same time means you have exponentially more states to encode data into, making quantum computers exponentially more powerful than traditional computers at binary code.

## Quantum entanglement

Another crucial property for the functioning of quantum computing is entanglement. It’s a somewhat mysterious feature of quantum mechanics that baffled even Einstein in his day who declared it “frightening action at a distance”.

When two qubits are generated in an entangled state, there is a direct measurable correlation between what happens to one qubit in one entangled pair and what happens to the other, regardless of their distance. This phenomenon has no equivalent in the classical world.

“This property of entanglement is very important because it brings much, much stronger connectivity between the different units and qubits. Thus, the elaboration power of this system is stronger and better than that of the classical computer”, said Alessandro Curioni, director of IBM Research. Lab in Zurich, explained to Euronews Next.

In fact, this year, the Nobel Prize in Physics was awarded to three scientists, Alain Aspect, John Clauser and Anton Zeilinger, for their experiments in entanglement and advancing the field of quantum information.

## Why do we need quantum computers?

So, in an admittedly simplified word, these are the building blocks of how quantum computers work.

But once again, why do we necessarily need such hyper-powerful machines when we already have supercomputers?

“[The] the quantum computer is going to make it much easier to simulate the physical world,” he said.

“A quantum computer will be able to better simulate the quantum world, therefore simulation of atoms and molecules”.

As Curioni explains, this will allow quantum computers to aid in the design and discovery of new materials with bespoke properties.

“If I can design a better material for energy storage, I can solve the problem of mobility. If I can design a better material for fertilizer, I can solve the problem of hunger and of food production. If I am able to design a new material that allows [us] do CO2 capture, I am able to solve the problem of climate change,” he said.

## Undesirable side effects?

But there could also be unwanted side effects to consider as we enter the quantum age.

One of the main concerns is that the quantum computers of the future could have such powerful computing power that they could break the encryption protocols fundamental to internet security that we have today.

“When people communicate over the internet, anyone can listen in on the conversation. So they have to be encrypted first. And the way encryption works between two people who haven’t met is that they have to lean on algorithms known as RSA or Elliptic Curve, Diffie-Hellman, to exchange a secret key,” explained Vadim Lyubashevsky, a cryptographer at the IBM Research Lab in Zurich.

“Exchanging the secret key is the hardest part, and it requires mathematical assumptions that break with quantum computers.”

In order to protect against this, Lyubashevsky says that organizations and state actors should already update their cryptography to quantum algorithms, ie. those that cannot be broken by quantum computers.

Many of these algorithms have already been built and others are under development.

“Even if we don’t have a quantum computer, we can write algorithms and we know what it will do once it exists, how it will run those algorithms,” he said.

“We have concrete expectations of what a particular quantum computer will do and how it will break certain encryption schemes or certain other cryptographic schemes, so we can certainly prepare for things like that,” Lyubashevsky added.

“And that makes sense. It makes sense to prepare for things like that because you know exactly what they’re going to do.”

But then there is the problem of data that already exists and has not been encrypted with quantum algorithms.

“There is a very great danger that government organizations are already storing a lot of internet traffic in the hope that once they build a quantum computer, they will be able to decipher it,” he said. .

“So even though things are still secure now, maybe something is being transmitted now that’s still interesting ten, 15 years from now. And that’s when the government, anybody building a quantum computer, will be able to decrypt it and perhaps use this information which it should not use”.

Even so, weighed against the potential benefits of quantum computing, Lubashevsky says these risks shouldn’t stop the development of these machines.

“Breaking cryptography isn’t the goal of quantum computers, it’s just a side effect,” he said.

“It will hopefully have many more useful uses, like increasing the rate at which you can discover chemical reactions and using them for medicine and things like that. So that’s what a quantum computer is all about. “, he added.

“And of course that has the negative side effect of breaking cryptography. But that’s no reason not to build a quantum computer, because we can fix that and we’ve fixed it. So that’s a kind of easy to solve problem there.”.

**For more on this story, watch the explainer video in the media player above.**

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