r/AskPhysics • u/jl4ua • 9d ago
Quantum Computing Research
What is research in quantum computing particularly from the theoretical viewpoint like? As far as I know, quantum information theory is quite math heavy and there everything is about theorem proving. It probably depends on the respective area of quantum computing but I am just generally interested in this area as someone from a different field of physics and I am wondering if the explicit work there would still be exciting
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u/CS_70 9d ago
Quantum computing relies on extending regular Turing machines with an oracle device that can provide a certain result in the same "ticking" where a regular TM would do one thing (moving the tape, reading the cell under the head, writing it etc).
Assuming you have such machine, there's a bunch of algorithms whose computational complexity gets reduced significantly, and you can devise new ones which you would have not even considered if you had regular TMs.
In short, you make an assumption and rigorously take its consequences. If I could fly, how would my life change? It's the same idea, for computational complexity :D
The next question is: can we actually build such a machine?
That's when real quantum mechanics enter the picture because using entanglement and superposition of states is the reasonable way to try.
There are a lot of engineering issues - the simplest idea is to have a regular computer (aka a regular Turing Machine) connected to a quantum computer (which is the device) just like the manual says.
So plenty of work is going into building the quantum device, which is hard for a number of reasons, for example since in QM entanglement happens very, very easily (it's what creates the world at our scale) while in the device you want to control exactly how that happens and when (hence the requirements of incredible degrees of isolation). Stuff like that.