Quantum computing takes advantage of the strange ability of subatomic particles to exist in more than one state at any time. Due to the way the tiniest of particles behave, operations can be done much more quickly and use less energy than classical computers.

In classical computing, a bit is a single piece of information that can exist in two states – 1 or 0. Quantum computing uses quantum bits, or ‘qubits’ instead. These are quantum systems with two states. However, unlike a usual bit, they can store much more information than just 1 or 0, because they can exist in any superposition of these values.

A qubit can be thought of like an imaginary sphere. Whereas a classical bit can be in two states – at either of the two poles of the sphere – a qubit can be any point on the sphere. This means a computer using these bits can store a huge amount more information using less energy than a classical computer.

#### What can Quantum Computers do that normal ones can’t?

Quantum computers operate on completely different principles to existing computers, which makes them really well suited to solving particular mathematical problems, like finding very large prime numbers. Since prime numbers are so important in cryptography, it’s likely that quantum computers would quickly be able to crack many of the systems that keep our online information secure. Because of these risks, researchers are already trying to develop technology that is resistant to quantum hacking, and on the flipside of that, it’s possible that quantum-based cryptographic systems would be much more secure than their conventional analogues.

Researchers are also excited about the prospect of using quantum computers to model complicated chemical reactions, a task that conventional supercomputers aren’t very good at all. In July 2016, Google engineers used a quantum device to simulate a hydrogen molecule for the first time, and since them IBM has managed to model the behaviour of even more complex molecules. Eventually, researchers hope they’ll be able to use quantum simulations to design entirely new molecules for use in medicine.

#### The effects that Quantum Computing will have in the future.

- Complicated optimization problems, such as calculating how to deliver packages in the shortest time while using the least energy. “Optimization problems occur everywhere at every company anywhere in the world,” Bacon said. Addressing those challenges could both save money and help the environment.
- Improving encryption technology by generating random numbers. Google’s quantum team is talking to its encryption key generation team about using a random-number generation tool it’s already developed for today’s Sycamore machine.
- Building machine learning systems better at tasks like distinguishing between real and fake items like bogus political videos. This was the original impetus for Neven’s work, and Google researchers think it could be the first area to deliver on quantum computing’s promise.
- Perhaps most interesting, simulating the real physics of molecular-scale materials. Revolutionary developments there could mean more efficient solar panels, a new way to produce nitrogen fertilizer without needing so much energy and better electric car batteries.

**Google’s Quantum Supremacy**

Google published a scientific paper in the journal Nature detailing how its quantum computer vastly outpaced a conventional machine, an idea called quantum supremacy. Powered by a Google-designed quantum processor called Sycamore, it completed a task in 200 seconds that, by Google’s estimate, would take 10,000 years on the world’s fastest supercomputer.