Dr. Nathan Flack and Dharma created De-quantified-plasma. After Flack became the first bang baby he went by the name Dr. Nemo. The name of the gas used during the Big Bang was never revealed until the Shadow War crossover in Milestone comics. It was revealed that Quantum Juice was purposely used so that characters such as the Blood Syndicate and Static would be created.
Dharma, the leader of the Shadow Cabinet, was the man who arranged it all because he saw creating these heroes was the only way for humanity to live on. He needed them to fight against Star Chamber and prevent them from creating missiles with Quantum Juice.