# What questions should be on topic for Quantum Computing?

Proposal: Quantum Computing

This is taken (with minor edits) from an old discussion post I had for the Quantum Computers proposal after it closed and before it was deleted; the question links are dead, but I'll leave them anyway, just for reference to old types of questions and the blue format is nice. I'm not saying they're all good questions, I'm merely using them as examples of categories of questions.

Essentially this post is to help people come up with 'good' questions, and by that I mean ones that will be upvoted to help get the proposal out of the Definition stage which is where it was closed last time round.

I think in its initial stages there need to be a range of questions that are deemed acceptable, and potentially answerable, to fit with the range of people and their backgrounds that might be interested in a potential Quantum Computing Stack Exchange. Considering some questions from the old proposal, they could possibly be categorised as follows:

I think on the subject of what might be considered 'Homework'-esque questions from the point of view of physics.se, could be welcome here, provided it's not actual homework. What I mean is the following, Physics students studying topics relation to quantum computing or quantum information are most likely in later years of their undergraduate (needing some quantum mechanics at least), or possibly postgraduate and may have some trouble with a concept or calculation. It's not quite like calculating the final velocity of a pulley, or a collision, or the current in a circuit using ohms law. Maybe someone from a Computer Science background could comment on their equivalent of physics.se 'Homework' (if any)? It might be worth a discussion anyway.

It might also be useful to have explanatory questions like the following:

• How can you entangle photons by making a measurement? An answer might involve mentioning the Barret-Kok scheme or a simplified version of it, where if you have two separate copies of states |0>+|1> and make a joint measurement (same or different) you can collapse the state into |00>+|11> or |01>+|10>. - This was something I came across recently and found interesting.

• or maybe some extra clarifications on how the game Quantum Moves works or the physics behind it. (I came across it but yet to try it myself.)

I think in order to structure feedback to this post, comments can go in the comments section, long discussions can probably be moved to chat.

Answers should address some specific issue, or some specific aspect of questions for the proposed site, or even some ideas/topics for possible questions e.g. questions about anyons are good/bad; a bit vague, but you get the idea.

If we try limit one topic per answer the followers of the proposal can upvote and downvote ideas and issues they agree and disagree with respectively.