Quantum Slipstream
Quantum slipstream technology is one of the most advanced propulsion systems ever encountered by Starfleet.

The quantum slipstream is an extremely powerful means of propulsion that can transport a vessel at speeds in the upper warp 9.9 range. The velocities involved are so great that, in theory, the slipstream could carry a ship across the galaxy in a single day. The quantum slipstream is actually a narrowly focused, directed warp field that is initiated by manipulating the fabric of the space-time continuum at the quantum level. It works by focusing a quantum field through a deflector dish to generate massive changed in local space curvature; this creates a subspace tunnel, which is projected in front of the vessel. Once a ship has entered this tunnel, the forces inside propel it at incredible speed.

The slipstream is large enough to accommodate more than one vessel, so a ship can enter the slipstream and accompany the vehicle this is generating it. In order to initate a controlled shutdown of the quantum drive, the field strength has to be reduced by 50 percent. This can be done by reversing the drive's polarity. The only fully functioning slipstream drive was enountered by the crew of the USS Voyager NCC-74656 in 2374. It was under the control of an alien called Arturis who belonged to an advanced race that had been assimilated by the Borg. In order to maintain the slipstream a ship has to constantly modify the quantum field with its deflector dish; however, the calculations involved are too complicated, and the time available too short, for current Starfleet technology.