SurfaceCode

Hmmmm. I'm not sure. I can't seem to access it any more either. Sorry! :(

Check out Umesh Vazirani's course from UC Berkley's open courseware. It's accessible.

Likewise, you don't ever explore the entire state space when you perform quantum computation. As it happens, most states are inaccessible. As shown by Poulin et al. in Physical Review Letters, 106, 170501 (2011), you can only ever explore a very small fraction of quantum states in polynomial time.

Edit: tezthenerd has said pretty much the same thing below. I just included the reference in case you'd like a formal proof.

Scott,

Do you think it's a good idea that all the teams working on quantum computing have put their money on the surface code? What are your thoughts? Do you believe that we are putting all our eggs in one basket?