What is quantum computing and how will quantum computers change the world?

Depending on who you ask, some say quantum computers could break the internet, making virtually all data security protocols obsolete, or get us out of the climate crisis.

These hyper-powerful devices, an emerging technology that exploits the properties of quantum mechanics, are much talked about.

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 built in just 2021.

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But what is all this fuss about?

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

Quantum technology proponents say these machines could usher in rapid advances in fields such as drug discovery and materials science, a prospect that hints at the tantalizing possibility of creating, for example, lighter and more efficient electric vehicle batteries or materials that could facilitate effective CO2 capture.

With the climate crisis looming and technology with the hope of solving complex problems like these are bound to generate keen interest.

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 aiming to take their place in a quantum future.

How do quantum computers work?

Given that these utopian-sounding machines are attracting such frenzied interest, perhaps it would be helpful to understand how they work and what differentiates them from classical computing.

Take every device we have today, from smartphones in our pockets to our most powerful supercomputers. These operate and have always operated on the same principle as the binary code.

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

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

But a quantum computer?

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These machines work completely differently. Instead of bits in a classical computer, the basic unit of information in quantum computing is the so-called quantum bit, or qubit. These are typically subatomic particles such as photons or electrons.

The key to a quantum machine’s advanced computational 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, global leader for advanced algorithms for quantum simulations at the IBM Research Lab in Zurich, told RockedBuzz via Euronews Next.

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

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

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

When at rest a penny has two sides, heads or tails. But if you flip it? Or spin it? In a sense, it’s heads and tails at the same time until it lands and you can measure it.

And for computing, this ability to be in multiple states at once means you have exponentially more states in which to encode data, making quantum computers exponentially more powerful than traditional binary-coded computers.

Quantum entanglement

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

[The] the quantum computer will make simulating the physical world much easier.

When two qubits are spawned in an entangled state, there is a direct 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 entanglement property is very important because it brings a much, much stronger connectivity between the different units and qubits. So the processing power of this system is stronger and better than the classical computer”, Alessandro Curioni, director of IBM Research Lab in Zurich, explained to RockedBuzz via Euronews Next.

Indeed, this year, the Nobel Prize in Physics has been awarded to three scientists, Alain Aspect, John Clauser and Anton Zeilinger, for their entanglement experiments and advances in the field of quantum information.

Why do we need quantum computers?

So, in a admittedly oversimplified nutshell, these are the building blocks of how quantum computers work.

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

“[The] the quantum computer will make simulating the physical world much easier,” he said.

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

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

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

Unwanted side effects?

But there may also be some unwanted side effects that need to be explained as we enter the quantum age.

A primary concern is that quantum computers of the future could be equipped with computational capabilities so powerful that they can break the encryption protocols critical to the security of the Internet that we have today.

“When people communicate on the internet, anyone can listen to the conversation. So they have to be encrypted first. And the way encryption works between two people who haven’t met is 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.

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“Exchanging the secret key is the hard part, and those require some mathematical assumptions that break with quantum computers.”

To protect against this, Lyubashevsky says organizations and state actors should already upgrade their encryption to secure quantum algorithms, e.g. ones that cannot be broken by quantum computers.

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

Sure, it has the negative side effect of breaking encryption. But that’s no reason not to build a quantum computer, because we can fix it.

“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 execute these algorithms,” he said.

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

“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 already existing data that hasn’t been encrypted with secure quantum algorithms.

“There is a very big danger that government organizations right now are already storing up a lot of Internet traffic in the hope that once they build a quantum computer they will be able to crack it,” he said.

“So even though things are still secure now, maybe something is being broadcast now that’s still interesting in ten, 15 years. And that’s when the government, whoever builds a quantum computer, will be able to decrypt it and maybe use that information which he shouldn’t use”.

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Nonetheless, compared with the potential benefits of quantum computing, Lyubashevsky says these risks shouldn’t stop the development of these machines.

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

“Hopefully it will have a lot more useful utilities like increasing the rate at which chemical reactions can be discovered and used for medicine and things like that. So that’s the point of a quantum computer,” he added.

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

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