A brief introduction to quantum computing | Hacker News Reader

A brief introduction to quantum computing

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94 pointsfriedrich1217 comments

Quantum computing is all about the tensor product. This is, roughly, how "and" works in the quantum world. Learning about tensor products by calculating with matrices is dizzyingly complicated [1]. But there's another way, using string diagrams [2].

[1] https://en.wikipedia.org/wiki/Kronecker_product [2] https://arxiv.org/abs/0908.1787

Quantum computing being all about the tensor product is like saying state-of-the-art image recognition is all about matrix multiplication.

There is a hell of a lot more to it.

I wouldn’t say the tensor product is how “and” works. “and” usually refers to the Boolean and operator. The tensor product is how combining two systems works. In classical computing, if you have:

int a; int b;

The set of possible states is the Cartesian product of the states of a with the states of b. In quantum computing, it’s the tensor product instead. It’s not terribly complicated to work with the matrices — they’re just huge. Fortunately, it’s not usually necessary to write out the matrices at all.

I read the string diagram paper. It’s supposed to be comprehensible to kids, but I couldn’t make heads or tails of it.

(I did my Ph.D. on quantum computing.)

I don't want to sound like a jerk or anything but you'd think that if a high schooler could write an entire paper like this about quantum computing of all things they'd be able to spell a few more things correctly, get basic punctuation right, grammar, etc.?

Phrased another way this is a great example of why the breakdown of a cumulative score (verbal vs quant, etc) is important on standardized tests.

Maybe you would, but I wouldn't. First, those are unrelated skill sets. Second, lots of people excel in one area and suck in another. That's completely normal.

>Quantum computing is a chance a solving problems that are considered unsolvable classical computers. Quantum computing is a relatively new and complicated field in this paper I provide a brief overview of quantum computing systems.

I agree, the abstract doesn't even make sense and has run-ons.

It looks like they didn't even bother to run it through spell check. I must admit their formatting is very nice. It looks like they might have used LaTex.

Since they don't proofread words effectively and missed simple mistakes like 'silt' for 'slit', it makes me doubt that the formulas have been proofread thoroughly, either.

Those things become far less important as your thinking becomes more attractive for others to read. Also plenty of people don't do their own editing.

It was a jarring read seeing those basic mistakes. Even just a once-over before publishing to web would have likely caught those typos and increased the credibility of the paper. Perhaps the author was tight for timeline or couldn't source a peer reviewer.

It was due on the day I finished it. Sorry for the grammar mistakes.

i once read about a theory of matter where under the right circumstances a larger system of quantum particles may act in a way consistent to a system composed of fewer particles. The larger solution approaches an exchange of, say, one electron or photon when really it’s an exchange of many particles. Does anyone know the name for that area of study?

To answer my own question: quasiparticles

I can’t help but think that may be a more tractable QC construction.

Unfortunately, things are quite a bit more complicated than this. The current issues in quantum computing aren't so much that it becomes difficult to describe a many-qubit system, but that those qubits individually (and pair-wise) aren't well controlled, and we just aren't good at coming up with many algorithms given these constraints.

Yes, and I’m wondering whether the current qubits are too fragile. Like whether there’s a way to construct a qubit out of a more naturally rebalancing system - somewhat analogous to an acid base buffer.

This is really impressive for a high school student.

for a great primer on quantum computing see https://docs.microsoft.com/en-us/quantum/quantum-concepts-4-...

non-commutative geometry will ruin his life.

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