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m3kw9yesterday at 8:59 PM5 repliesview on HN

Been trying for the longest time, I still don’t understand how quantum computing work. It’s always something-something tries all possible combinations and viola, your answer.


Replies

Chabsffyesterday at 9:11 PM

The whole "tries all possible combinations" thing is a very misleading oversimplification in the first place.

Instead, think of it more like a completely different set of operations than classical computers that, if you were to try and replicate/simulate them using a classical computer, you would have no choice but to try all possible combinations in order to do so. Even that is oversimplifying, but I find it at least doesn't hint at "like computers, but faster", and is as close as making the parallelism pov "correct" as you're going to get.

What these operations do is pretty exotic and doesn't really map onto any straightforward classical computing primitives, which puts a pretty harsh limit of what you can ask them to do. If you are clever enough, you can mix and match them in order to do some useful stuff really quickly, much faster than you ever could with classical computers. But that only goes for the stuff you can make them do in the first place.

That's pretty much the extent I believe someone can "understand" quantum computing without delving into the actual math of it.

benchmarkistyesterday at 9:07 PM

Every quantum algorithm is a unitary operation in a Hilbert space. If you want to understand the theory then you will have to do the actual work of learning about Hilbert spaces and unitary operators.

show 2 replies
DarmokJalad1701yesterday at 10:51 PM

https://www.youtube.com/watch?v=F_Riqjdh2oM

This video is the simplest explanation that I have found for Quantum Computing which doesn't do the whole pop-sciency "is both zero and one at the same time" nonsense.

krackersyesterday at 9:39 PM

>It’s always something-something tries all possible combinations

"If you take nothing else from this blog: quantum computers won't solve hard problems instantly by just trying all solutions in parallel." - Scott Aaronson

This short comic he helped author actually summarizes the core idea fairly well https://www.smbc-comics.com/comic/the-talk-3

elpockoyesterday at 10:30 PM

>viola

A large violin provides little answers.