Originally published at: http://www.howtogeek.com/165730/how-does-a-quantum-computer-work/
If you are not familiar with quantum computers, then you may be wondering what the difference is between them and our regular everyday computers. Veritasium discusses the topic of what makes a quantum computer different and why they are so powerful in this video.
As clear as ... classical mud.
This was the clearest explanation of this otherwise, recondite topic, that I've ever seen. Professor Morello did a good job.
My head is spinning and there's a lot I don't understand; however, I did learn something new from the video. Actually two things:
- Quantum Computing relies on Probabilities
Qbits, quantum bits, can be in both states (on and off) simultanously because before you measure it, the electron is in a quantum superposition. In other words, before you actually measure the electron, there's a mathematical probability that the electron could be in a spin-up state, which is a 1 or a spin-down state which is a 0.
The part that used to confuse me was that it sounded like quantum computers defied the law of non-contradiction; namely, that something cannot both be A and non-A at the same time and in the same sense; however, I see now that this isn't a contradiction - it's just a way of accounting for probabilities. For example, before measuring the electron there could be a 53% chance that it's spin up and 47% probability that it's spin down.
By the way, spin-up and spin-down just refers to the orientation of the electron in the magnetic field. Spin-up means the orientation of the electron is such that it's postive pole is facing up. It's just a way of determining state.
- Quantum Computers are not Replacements for Regular Computers
This was the biggest discovery from the video: qauntum computers are not a replacement for regular computers because they're only faster for special calculations that can use all the quantum superpositions (those spin-up/spin-down probabilities) available to you. It doesn't speed up the internet or result in higher definition video.
The real benefit of quantum computers is that the number of operations to arrive at the result is smaller NOT the speed of each individual operation itself. Quantum science just let's you get there with less work but this only applies to very specific calculations and therefore can't be used as a panecea to universally speed up computers.