Depending on who you ask, some say that quantum computing could either destroy the internet and render pretty much every data security protocol obsolete, or allow us to calculate our way out of the climate crisis.
Everyone is talking about these hyper-powerful devices, an emerging technology that exploits the properties of quantum mechanics.
Just last month, IBM unveiled its latest quantum computer, the Osprey, a new 433-qubit processor that’s three times more powerful than its predecessor, which was only built in 2021.
But what’s all the hype about?
Quantum is a field of science that studies the physical properties of nature at the level of atoms and subatomic particles.
Advocates of quantum technology say these machines could herald rapid advances in areas such as drug discovery and materials science — a prospect that opens up the tantalizing possibility of developing, for example, lighter, more efficient batteries for electric vehicles or materials that could enable effective CO2 capture .
With the climate crisis looming, technologies hoping to solve complex problems like these are bound to attract a lot of interest.
It’s no wonder, then, that some of the world’s biggest tech companies — Google, Microsoft, Amazon, and of course IBM, to name a few — are investing heavily in it, trying to secure their place in a quantum future.
How do quantum computers work?
Given that these utopian-sounding machines are attracting such frantic interest, it might be useful to understand how they work and how they differ from classical computing.
Take every device we have today – from the smartphones in our pockets to our most powerful supercomputers. These work and have always worked according to the same principle of binary code.
Essentially, the chips in our computers use tiny transistors that act as on/off switches to provide two possible values, 0 or 1, also known as bits, short for binary digits.
These bits can be configured into larger, more complex units, essentially long strings of zeros and ones encoded with data commands that tell the computer what to do: display a video; view a Facebook post; play an mp3; let you enter an email and so on.
But a quantum computer?
These machines work very differently. Instead of bits in a classical computer, the basic unit of information in quantum computing is what is known as a quantum bit or qubit. These are typically subatomic particles such as 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 global head of advanced algorithms for quantum simulations at the IBM Research Lab in Zurich, told Euronews Next.
“Rather than just having the two levels zero and one, which you would have in a classical calculation here, we can build a superposition of these two states,” he added.
Superposition in qubits means that a qubit in superposition can be 0 or 1 or 0 and 1 at the same time, in contrast to a binary system with its two possible values 0 or 1.
And if you can’t picture that, the analogy often given is that of a penny.
When stationary, a penny has two faces, heads or tails. But if you flip it? Or rotate? In a way, it’s heads and tails at the same time until it lands and you can measure it.
And for computing, that ability to be in multiple states at once means you have an exponentially larger set of states in which to encode data, making quantum computers exponentially more powerful than traditional binary-code computers.
Another crucial property for how quantum computing works is entanglement. It’s a somewhat mysterious feature of quantum mechanics that baffled even Einstein at the time, who called it “eerie action at a distance.”
When two qubits are created in an entangled state, there is a directly measurable correlation between what happens to one qubit in an entangled pair and what happens to the other, no matter how far apart they are. 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 entities and qubits. The processing power of this system is therefore stronger and better than that of the classic computer,” says Alessandro Curioni, director of IBM Research Lab in Zurich, told 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 on entanglement and advances in the field of quantum information.
Why do we need quantum computers?
So these are, admittedly in simplified terms, the building blocks of how quantum computers work.
But again, why do we absolutely need such hyper-powerful machines when we already have supercomputers?
“[The] Quantum computers will make simulating the physical world much easier,” he said.
“A quantum computer will be able to better simulate the quantum world, i.e. the simulation of atoms and molecules.”
As Curioni explains, this will allow quantum computers to help design and discover new materials with tailored properties.
“If I’m able to design a better material for energy storage, I can solve the problem of mobility. If I’m able to design a better material than fertilizer, I can solve the problem of hunger and food production, and I’m able to design a new material that allows it [us] By doing carbon capture, I am able to solve the climate change problem,” he said.
Undesirable side effects?
But there might also be some unwanted side effects that need to be considered as we enter the quantum age.
A key concern is that future quantum computers could have such powerful computational capabilities that they could break the encryption protocols that are fundamental to the security of the internet we have today.
“When people communicate over the Internet, anyone can overhear 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 rely on some algorithm known as RSA or Elliptic Curve, Diffie-Hellman, to exchange a secret key “, explained Vadim Lyubashevsky, cryptographer at the IBM Research Lab in Zurich.
“Exchanging the secret key is the hard part, and that requires some mathematical assumptions that are broken with quantum computers.”
To protect against this, Lyubashevsky says that organizations and state actors should already upgrade their cryptography to quantum-proof algorithms, ie. ones that cannot be broken by quantum computers.
Many of these algorithms have already been developed, others are under development.
“Even if we don’t have a quantum computer, we can write algorithms and we know what it’s going to do once it exists, how it’s going to run those algorithms,” he said.
“We have concrete expectations of what a given quantum computer is going to do and how it’s going to break certain encryption schemes or certain other cryptographic schemes. So we can definitely prepare for things like that,” added Lyubashevsky.
“And that makes sense. It makes sense to prepare for things like this because we know exactly what they’re going to do.”
But then there’s the problem of pre-existing data that hasn’t been encrypted with quantum-safe algorithms.
“There is a very high risk that government organizations are already storing a lot of internet traffic in hopes that once they build a quantum computer, they can decode it,” he said.
“Even though things are safe now, maybe something is being broadcast now that will still be interesting 10, 15 years from now. And then the government, whoever builds a quantum computer, will be able to decode it and maybe use that information “he shouldn’t be using”.
Still, weighed against the potential benefits of quantum computing, Lyubashevsky says these risks shouldn’t stop the development of these machines.
“Cracking cryptography is not the point of quantum computing, it’s just a side benefit,” he said.
“Hopefully it will have many more useful tools, like increasing the speed at which you can discover chemical reactions and use them for medicine and the like. So that’s the point of a quantum computer,” he added.
“And sure, it has the negative side effect that it will break cryptography. But that’s no reason not to build a quantum computer, because we can patch that and we’ve patched that. So this is an easy problem to solve”.
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