A phase-conjugate graviton beam was a graviton beam that was intended to close the Bajoran wormhole without damaging it or harming the Prophets. The beam was devised by Lenara Kahn of the Trill Science Ministry. In 2374, William T. Riker suggested that the crew of the USS Enterprise use a phase-conjugate graviton beam to close a wormhole, created by Lem Faal, that the entity 0 was using to enter the galaxy. (TNG - The Q Continuum novel: Q-Strike)