Apologies for asking such a basic question, but Google search seems incapable of addressing it correctly:

Do (or will) quantum computers ever require password protection of their own? Or are they their own protection?

Many thanks.

That would depend on the needs and desires of the people with the device. There’s nothing inherent in a QC that makes them resistant to an unauthorized person using it.

In addition to the above, QC is not a general-purpose computer and it supposed to operate under instructions from a classical computer. The latter of course should have all usual protections.

Thanks for that. So assuming for argument's sake that QCs were to become general purpose PCs at some point in the future, would it then be correct to assume they would indeed require a password. . . if only to protect them from being hacked into by other QCs?

I think so. Some kind of a "key".