An Interphasic Field Generator is a device that can be used to create an artificial Interphasic Rift. This device was originally used to test the initial concepts of the Phase Cloaking Device later developed for use by the USS Spectre.
The devices were large and required a great deal of energy to function. In fact, a normal Starship could not deploy them because of the energy requirement.
However, in 2408, the USS Rosenante installed such a device aboard the ISS Rosenante. This ship could power such a device, because like their prime universe counter parts, they possessed a pair of Warp Cores rather than a single warp core as is found on most star ships.
When the device was activated, it forced the ISS Rosenante back to their own universe, the Mirror Universe.