ANTIMATTER FUEL. “The energy per unit mass (9×10(16) J/kg) is about 10 orders of magnitude greater than chemical energies, and about 3 orders of magnitude greater than the nuclear potential energy that can be liberated, today, using nuclear fission (about 200 MeV per fission reaction or 8×10(13) J/kg), and about 2 orders of magnitude greater than the best possible results expected from fusion (about 6.3×10(14) J/kg for the proton–proton chain).
https://en.m.wikipedia.org/wiki/Antimatter