What makes quantum computing so hard to explain?

Re:What makes quantum computing so hard to explain? by reikonomusha on Wednesday June 09, 2021 @12:16AM (#27444160)

I consider simulating a coin flip (aka creating a so-called “even superposition”) to be the hello world of quantum computing. In a quantum programming language called Quil, this looks like

    DECLARE result BIT
    H 0
    MEASURE 0 result

This will put a 0 or a 1 in result with equal probability. ‘H 0’ is performing a Hadamard operation on qubit 0. The MEASURE allows us to extract a classical bit value out of a qubit.

Others might say the “Bell pair” is the hello world, and that looks like this:

    H 0
    CNOT 0 1

This is a bit harder to explain, because it requires understanding both superposition and entanglement.

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Re:What makes quantum computing so hard to explain? by krastanov on Wednesday June 09, 2021 @10:06PM (#27455938)

I am just being annoyingly pedantic, but I do not think a Clifford circuit (both of your examples fall in this category) is a good quantum hello world, because they are trivial to simulate efficiently on a classical computer. But I do not have better suggestions.

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Re:What makes quantum computing so hard to explain? by chunky1994 on Wednesday June 09, 2021 @10:20PM (#27456009)

I don't think a "hello world" type of program/circuitry(?) needs to be unique to a quantum computer. It just needs to be expressible with a quantum circuit.

Similar to how you can have hello world in both ruby and python, but arrive at them with different syntax and compilers.

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Re:What makes quantum computing so hard to explain? by Bjartr on Thursday June 10, 2021 @08:30AM (#27459861)

And displaying "Hello World" can be done trivially with a pencil and paper. That doesn't make doing so in a classical programming language devoid of value.

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Re:What makes quantum computing so hard to explain? by krastanov on Thursday June 10, 2021 @12:58PM (#27462875)

Sure, but there is value in a "Hello World" being focused on what is special about the hardware/language. Look at Haskell and OCaml tutorials for instance: they all explicitly say stuff like "let us start with the 'Hello World' of functional languages, namely, implementing the Fibonacci (or factorial) function recursively".

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Re:What makes quantum computing so hard to explain? by josefx on Thursday June 10, 2021 @06:24AM (#27459045)

Isn't that the case for literally anything you could run on the current state of the art quantum computers?

The troll answer of simulating a qbit using a qbit excluded.

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