I don't believe the tag meta-physics is a good one for this site. Firstly, such questions generally are more philosophy based, and thus don't really belong here, so having this tag seems to encourage off topic questions. Second, the only question that bears this tag is not really much better categorized with it, at least for quantum computing experts. Finally, I believe this tag could very well drive off experts. Thoughts?
These are the top definitions I come up with when I google "metaphysics+definition":
the branch of philosophy that deals with the first principles of things, including abstract concepts such as being, knowing, identity, time, and space.
abstract theory with no basis in reality
So yes, I don't think that tag should exist. As a rule of thumb, avoid creating tags which, if used as a stand-alone tag on a question, would probably make the question unsuitable for this site. To solidify it for this case "pure" meta-physics questions aren't suitable for this site. We are a technical site and should avoid opinion-based philosophy discussions, which questions about meta-physics would likely bring about. Also, I can already imagine the large possibility of misuse of that tag, by newcomers to the site.
Update: I've removed the meta-physics tag from this question. That was the only question which was using it. If someone has any objection to this and/or a strong reason as to why the tag should be kept, feel free to let me know in the comments.