A dekyon is a subatomic particle with subspace qualities. Dekyons can be emitted through a starship's deflector dish via a dekyon beam. The projection of a dekyon beam over a distance of fifty million kilometers requires a great amount of energy.
In 2368, a dekyon field was partly responsible for recording signals from the USS Enterprise (including the voices of the crew) when they were trapped in a temporal causality loop. (TNG: "Cause and Effect")