(coexisting on another dimensional plane)
In the mirror universe, the Tantalus Field is an alien device that vaporizes victims at the touch of a button.
Hoshi Sato stole technology from Tantalus V and was able to construct a surveillance device allowing her to "neurally displace" any desired subject into a state of "non-being". Using this device, Sato was able to find the USS Defiant again and prepared to take it back to Earth to claim her throne once again.
In 2260, Lieutenant James Kirk discovers the Tantalus Field while leading an expedition on a dead planet. Kirk later uses it to become captain of the ISS Enterprise, by assassinating Captain Christopher Pike.
This Tantalus Field became regulatory on Terran starships during the 23rd century.