In memory alpha's page on the self-repairing minefield seen in Deep Space 9, it states in the 3rd paragraph of the background information section that, "As stored material [for replicating replacement mines] begins to run out the mines have a zero-point extraction system for matter replenishment." It does not, however, explain what a zero-point extraction system is. Is there any explanation for what this is, or how it works, and has it ever been seen elsewhere in the Star Trek universe?