Well, it takes quite a lot of energy, precisely because antimatter is compressed energy, lemme say that again ANTIMATTER IS COMPRESSED ENERGY, so, logically, it would need so much more energy in turn to produce antimatter
Well theres really no way of knowing how much energy it takes considering antimatter is only theoretical. But if it was proven I would assume it would be as powerful as a black hole, however powerful that is. Essentially antimatter is a dark hole if you think in terms of what its capable of.
On average, it currently takes about 10 billion times more energy to create antimatter than its equivalent energy (by Einstein's equation, energy equals mass times the speed of light squared). Improvements in efficiency are possible and are being considered.
