Quantum Computing| What is Quantum Computers?
By: Supun Shanaka
Tags: Quantum, Quantum Physics, Quantum Computing

Computers are getting a massive upgrade thanks to quantum physics. This is known as Quantum computing. So what are quantum computers, how do they work, and what do they mean for the future.

What are quantum computers?

Quantum mechanics is a field of physics that studies the behaviour of the most basic and smallest parts of our universe. At the subatomic level. Reality at this level is very different from the reality we experienced every day, but it is reality nonetheless. In the quantum world, weird things happen. Things that scientists are just now starting to try and understand. Even Einstein refers to what goes on here as spooky. Superposition is the phenomenon where particles can be in two states at the same time.

Imagine the coin that’s spinning on a table. At this present time, the outcome is both heads and tails at the same time. Imagine slamming your hand down over the coin, causing it to collapse into one outcome: head or tail. It’s basically the same idea with quantum particles.

Currently, computers use bits, which are either 0 or 1, to process information. But if we use quantum particles as data, something interesting happens. Using quantum particles called qubits and the property of superposition, they can read both like 0 or 1 at the same time. This makes the amount of data that can be represented exponentially greater. This allows quantum computers to process far more data than the classical computer will ever be able to do.

If a quantum computer had one hundred qubits, it would be more powerful for some applications than all supercomputers on earth combine. Three hundred qubits could hold more numbers simultaneously than there are atoms in the universe. So what could a billion qubits do?

Entanglement is another phenomenon where two particles can be linked. So that one particle always gives the same outcome as the other. Imagine two entangled quantum dies. Even if those separated on opposite sides of the earth, when rolled, they would show the same results as each other every single time. It’s still being debated, but entangled particles could mean that communication could be instant, regardless of the distance between the particles. It could be greater for security too. Since it potentially doesn’t use any physical infrastructure to transfer this information. This means in the future, it may be impossible for communication to be intercepted or hacked without the knowledge of the information owner. Classical computers use logic gates to run functions, which take inputs and produce an output. This may produce a one if both inputs or a one. And “OR” gates produce and if at least one of the inputs is a one. Quantum gates, however, can do a lot more.

The gates entangle, change probabilities, and collapse superposition qubits to produce results. Simply put, they can run all possibilities at once. Normally on a classical computer, it would check all probabilities one by one. This all means that quantum computers can find a solution much faster. Especially on large datasets, but it goes far beyond this. If you want to model the world, we can encode physics rules into its operations on qubits, just like we use logic gate circuits on classical bits. It’s an incredible idea. It’s almost like pure coding physics into the fundamental essence of nature and reality. Not just some mathematical approximation of reality like we do now.

Quantum computers could simulate our universe, allowing us to model new molecules in the arrangement. We haven’t discovered and test them to find new materials. These new materials may help create another breakthrough in science and engineering never before thought possible, from new batteries and energy sources to super-strong materials and incredibly effective medicines.

So here is how it would work. We all know that the world is built up of atoms and molecules. So if we could simulate those accurately, we’ll well on the way to a new paradigm. In the real world, molecules are formed to an electron orbit overlap. To accurately model real electrons, you need to keep track of the fact that they can exist in multiple states at once. Although this fact can be expressed as a probability or chance, classical systems are a real problem. When the number of particles goes up, the number of possible states grows exponentially.

For ten electrons would need to track about a thousand possible states. But for a molecule or just 20 electrons would have to keep track of over a million different probability states. If we want to model a real physical system with millions of electrons, things quickly get out of hand. A modern laptop can model a 26 electron system. A supercomputer- 43 electrons. But what about a 50 electron system?

Well, forget it. That’s impossible for any classical computer in the future as far as humans will exist.

Nature and reality itself is a quantum system, and it can’t be modelled on a classical computer effectively. It all boils down to this. The information required to describe a quantum system can only be held by another quantum system. Because of the qubits, quantum computers are quantum and desire just like nature. They have no problem keeping up with nature’s exponential complexity. Consider the case of modelling different molecules. As you can see, when we get to molecules a bit more complex than benzene, the computational time to model them approaches infinity.

For a quantum computer, all you have to do is just add more qubits and the computational time scales linearly with the problem. So to solve this, we just simply add on another 50 qubits or so. For each qubit added, a quantum computer gets exponentially more powerful. If a quantum computer had millions of qubits, just imagine what molecule interactions we could simulate. There are even proposals that quantum computers could predict climate accurately or, for the first time, accurately model the human brain. The possibilities are endless.

So, of course, if we come back to reality, quantum computers in their infancy. Just like classical computers was in the 1950s. Back then, classical computers took up a whole room, and a modern quantum computer is at the same stage. There are still decades of breakthrough he remaining before any quantum computers can create some profound change. But the research is going ahead and not slowing down. So we don’t know what secrets of the universe we’ll unlock when we start simulating subatomic particles. The possible breakthroughs are as unknown as they are exciting. But one thing is sure. Quantum computers hold the potential for a radical change in the progress of humanity. Just like the steam engines and the internet and we could be looking back and marvelling at just how simple our lives once were. So that just about wraps our look at quantum computers.

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