Last updated on 13 February 2025
What is Quantum Computing?
Quantum Computing is a form of information processing using quantum theory. That is, the laws of physics work differently at subatomic levels. While not useful for all forms of computing, Quantum Computing is best employed for ‘needle in a haystack’ problems, such as balancing risk in investment portfolios, or calculating the most efficient delivery route for shipping.
Quantum Theory in computing?
Ever heard of Schrodinger’s Box? If Schrodinger was still alive today, he would be a big fan of quantum computing. While traditional computing uses absolute bits in 1’s and 0’s, quantum computing utilizes qubits, which are bits that both exist as 0 and 1 simultaneously. This is known as superposition, and is the main driving concept behind both Schrodinger’s Box, and quantum computing.
When in a superposition state, the qubits exist in both 1 and 0 at the same time. Only when the superposition state collapses can an interference pattern be observed and results can be drawn.
Look at this example from Scientific American of a mouse trying to get through a maze. There are many different routes, but only one will lead to the cheese. A traditional / classical computer would ‘guess and check’, by systematically evaluating one route at a time, then determining whether it was a pass or a fail. Depending on the complexity, this could take a lot of time. It’s like having a 3-digit combination lock and starting at 000, then moving to 001, then 002 until eventually something works.
But a quantum computer would apply the concept of superposition to test all routes at the same time. The qubits existing in both a yes/no state, and bouncing around off each other would explore each route.
Finally, when the superposition state collapses, an interference pattern where the solution can be observed emerges. In this example where there is only one correct path (and every wrong turn will lead to a dead end 100 of the time), there is an interference pattern with one strong result. In a situation where there are multiple correct routes, you will see each correct route, with the most efficient route being the most emphasized in the interference pattern.
Another example is if you have 10 people at a dinner party, and trying to figure out where people can sit:
It is easy enough to calculate how many different combinations there are. The formula for this is:
(n) x (n-1) x (n-2) ….. x (n-9) = 3,628,800
But what is each specific arrangement? This is where quantum theory comes into play. Quantum computing, when provided no additional information, can present each and every combination. Where it gets interesting however is when you apply other input. If you have 10 people, and add the conditions “Mark can’t sit beside Anna, and would prefer to sit beside Blake”, the interference pattern would eliminate any result where Mark sits beside Anna, and would emphasize every result where Mark is beside Blake. Apply more criteria / terms and it becomes clear which arrangement is the best or the most efficient.
How does a Quantum Computer work?
The trick that allows a computer to effectively be a quantum computer boils down to one major thing; cooling, but not the same cooling as what’s in your computer at home. For a quantum computer to work, the superconducting circuits need to be cooled down to near absolute zero (-273 degrees celsius, or -459 fahrenheit for the imperial-system folk), at which point the circuits inherit these quantum-like properties. No amount of air/water cooling solution you would employ in your computer rig at home or in a server rack setting would ever come close to this. To meet this requirement, a very specialized setup has to be used:
This is a quantum computer that IBM created. It hangs from the ceiling, and takes up a huge amount of space. The discs you see are called chandeliers, and there are many cables, filaments, and coils. Working in tandem with a specialized helium mixture, this machine operates to get those superconductors as close to absolute zero as possible.
IBM and other pioneers in the quantum computing space are faced with a glaring issue when it comes to developing this technology for wide use; scaling down the massive size of it. While progress is being made, costs still remain very high and size is reminiscent of the good ‘ole days where a computer would take up an entire room of your house.
Conclusion
If you ever need to crack a password or solve a problem with random guesses and attempts, head on down to your local computer store and ask to use their quantum computer… just kidding. Odds are it will still be a little while before these are seen and available for widespread use. In the meantime though, I hope you learned something about quantum computing!
Thank you for reading!
