Antigraviton
From Memory Alpha, the free Star Trek reference.
An antigraviton is a variant of a graviton particle. Tractor beams use heavy concentrations of antigraviton particles.
In 2370, a concentration of antigraviton particles was discovered in a USS Enterprise-D's transporter emitter coil, following the transport of Jean-Luc Picard and Beverly Crusher to the surface of Kesprytt III. Evidence suggested that the Prytt Alliance used a tractor beam to deflect the transporter beam from the Enterprise to a different set of coordinates. (TNG: "Attached")
During a Vidiian attack in 2371, Commander Chakotay ordered the USS Voyager's main deflector rerouted to discharge antigraviton pulses along the hull, in an effort to break the hold of the Vidiian grapplers. (VOY: "Fury")
In 2374, Damar developed a way to deactivate the self-replicating mines around the Bajoran wormhole individually using an antigraviton beam, projected by reconfiguring the field generators of Deep Space 9's deflector array and refocusing the emitters. (DS9: "Behind the Lines", "Favor the Bold")
In 2375, a Renovation Team Nova vessel, commanded by Supervisor Yost, sealed a subspace sinkhole using antigraviton beams. (VOY: "Gravity")
[edit] Background
Although gravitons have yet to be formulated as a mathematical construct, gravity waves are detectable in special circumstances. Given gravity's ambient planar/spatial distribution, it is assumed by physicists that a graviton would be its own anti-particle, in the style of the photon.
