Why is entanglement essential for quantum computing?

[zZhang]

Asked myself that question today, and I don't know what the answer is. Maybe I missed something somewhere in the math...

Anyone know?

[zZhang]

I suppose I should comment a bit further on my current line of thinking and why I don't see where entanglement has to appear in order for quantum computing to work.

Correct me if I'm wrong, but it appears that in order to do quantum computing, you either

1) Have an initial state, choose a Hamiltonian, and evolve the system according to Schrodinger's equation

2) Apply a series of unitary operators to an initial state.

Neither seems to require entanglement of states for it to work.