In the Unanswered questions section of the analysis for this episode, it asks: "Why did the SGC never attempt to use quantum mirror after Daniel returned from the alternate reality? " Listen my subjects for I hold the answer.
In the episode which the quantum mirror was discovered ("There But For The Grace Of God"), Danial found the controlling device next to the mirror. When he took it with him, he left it in the SGC in his rush to get to the gate because of the Goa'uld attack. He was able to return beause, as Kawolski explains in "Point of View", the mirror will keep two alternate realities connected until the device severs the connection, which Danial never did on his first trip.
Obviously, we can't even begin to try to make our own controlling device for the quantum mirror, so that may be why it was kept in Area 51.
Also in the Unanswered Questions section, it asks about the device Jack made. He made it using parts he found around the base and it was declared dead after O'Neill used it to go to the Asgard's homeworld. With two Carters open to build a copy of it, they could easily figure it out.