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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

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.

krastanov 5y ago
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.
- chunky1994 5y ago
  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.
- josefx 5y ago
  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.
- Bjartr 5y ago
  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.
  - krastanov 5y ago
    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".

krastanov 5y ago

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.

chunky1994 5y ago
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.
josefx 5y ago
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.
Bjartr 5y ago
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.
- krastanov 5y ago
  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".