Hawking Radiation originates from quantum fluctuations. These fluctuations 'borrow' energy from the universe and spawn a particle/anti particle pair. Normally, this pair would quickly annihilate each other, retuning the energy to the universe, thus preserving conservation of energy. However, when these pairs pop into existence straddling the event horizon, one will be unable to escape, and the other will not be able to annihilate and return its energy. For conservation of energy to remain, the particle that escapes must become a 'real' particle, thus it has positive energy, and the particle that is trapped in the black hole must have negative energy. This negative energy thus reduces the total energy of the black hole. The particle that escapes would appear to have been emitted by the black hole as the black hole lost energy. Now, this particle carries with it information entangled in its own state as to the state of the other particle that fell into the black hole. If the 'real' particle was an 'up', then we can assume the anti particle was a 'down' state.