Dirac jump

A Dirac jump was a change of energy states in subatomic particles.

After contact was first made with the mirror universe in 2267, Montgomery Scott wrote in his paper on the subject that Dirac jumps were one of the things that had occurred between the two realities. 

In 2269, Scotty explained to Leonard McCoy, who had stated that transporters turned matter into energy and then reconstituted it, that what the transporter actually did was analyze the energy state of each particle and produce a Dirac jump to a equivalent state.