Quantum Computers: Everything You Need To Know About Quantum Computing & Why It's A Big Deal

If you're a tech lover, or just really into science, Quantum computing may have come up a lot. The thing is, while it's important and seems to be the key to the future, the workings of it are a little opaque. So we're going to attempt to break it down for you.

The basics - Quantum Mechanics

The first thing you have to know is that quantum computers work on the principles of quantum mechanics. Quantum mechanics is the study of our universe at the subatomic level. Basically, it looks at the building blocks of reality and how they interact. These particles work in ways that may defy logic to you, and that's the reason it's so important. Given that, there are two main properties you need to know about

Superposition

Superposition is the ability of a quantum particles to exist in two states at once. Think of a closed box that's full of breakable plates. You drop the box and it clatters, at which point you don't know the state of the plates inside. Until you open up the box, they're both broken and unbroken at the same time. If you open the box though, you can see for yourself that the plates are either broken or not. It's when they're hidden in their dual state that they most resemble superposition.

Superposition is like a coin that will never stop spinning

Entanglement

Quantum entanglement is described as a sort of connection between two subatomic particles, such that each of them are both always in the same state. For instance, consider two dice that are taken to opposite sides of the world. In quantum entanglement, if you roll a six on one die, the other is also showing a six.

In the future, if we figure out a way to exploit this, we could conceivably develop a medium a communication that's faster than light. This sort of concept exists in the sci-fi series 'Ender's Game', where there exist communication devices called ansibles that exploit the quantum entanglement of subatomic particles. That way, when you're manipulating the particle at one end, the information is immediately represented at the other without delay. It also doesn't use a physical medium to transfer this data, meaning it can't be intercepted.

IBM's Q quantum computer

Quantum computers

Now, what you probably know is that classical computers use something called bits to store information. Data in bits is represented as either a one or a zero. Quantum computers however use something called qubits. Thanks to superposition, these qubits can exist in a state of both one and zero, thereby exponentially increasing the amount of data a quantum computer can represent. As such, they can also process more data much faster than classical computers

It's estimated that a quantum computer with 100 qubits would be more powerful than every supercomputer currently on Earth combined. WIth 300 qubits, such a machine could hold more numbers simultaneously than there are atoms in the universe.

Logic gates

Classical computers use logic gates to run functions, which basically take input and run it through a check provided to give an output. In the gates below, the AND gate outputs a 1 if both source values are 1. The OR function outputs a 1 if either one of the source values is 1.

Quantum gates however go far beyond simple AND/OR however; they can run all possibilities at once. So when a normal computer checks all probabilities one by one, a quantum computer can run them simultaneously. Therefore, it processes calculations much faster, more so the larger the data set is.

Understanding the speed comparison

Think of computing versus quantum computing as a cycle race. The two participants, one of a classical cycle and one on a quantum cycle, have to race to a certain point that has a mountain in between. When the starting pistol goes off, the rider on the classical cycle does the only logical thing, and starts cycling up the mountain, knowing he'll have to go down the other side to get to the finish line. The rider with the quantum cycle instead decides he's just going to go straight through the mountain, and is therefore done with the race a long time before his competitor. That's exactly why quantum computing is so important to the future of pretty much everything.

What is it good for?

A quantum computer wafer

Because of how well it can process large amounts of data, quantum computing seems to be invaluable to future research in most every field imaginable. For instance, think of how we might simulate molecules. Molecules form when the electrons in one or more atoms overlap in their orbits. So simulating a molecule means keeping track of all the electrons in each atom. The more complex the molecule, the more variables you need to keep track off.

Classical computers quickly overload in the face of this sort of data. The average modern laptop can keep track of 26 electrons and their bonds, and a supercomputer 43. With quantum computers however we could simulate incredibly complex molecules, the likes of which we haven't even imagined yet. That could lead to massive breakthroughs in drug manufacturing, material science, and bio-engineering.

We're still years, possibly decades away from a big jump in quantum computing. At the moment, one of the most advanced quantum computers on Earth holds only 79 qubits. But as that number goes up, we might even have the processing power to simulate reality as we know it.