This is plain wrong. It just can't work. Did you try it before posting? Do you know what \Q is for? (It's for escaping regexp metacharacters from strings interpolated in regexen.)

From perlop, section Quote and Quote-like Operators:

You cannot include a literal "$" or "@" within a "\Q" sequence. An unescaped "$" or "@" interpolates the corresponding variable, while escaping will cause the lit- eral string "\$" to be inserted. You'll need to write something like "m/\Quser\E\@\Qhost/".