for the following implementation of FANOUT using Toffoli gates, I'm confused about the follows:
- "the second bit being the input to the FANOUT and the other two bits standard ancilla states" - does it mean that the second bit is also the input to the other two ancilla states? Why do ancilla states require any inputs, aren't they pre-determined?
- Why does the output from FANOUT appear on the second and third bits? How do we extract and use this output? I learned FANOUT with the following definition and diagram. Thus, is the value of a outputted from our circuit with Toffoli gate the value of N in the above diagram? Isn't a either 0 or 1? Then does it mean the value for fan-out can only be 0 and 1? I didn't think so as it's there are clearly more than 1 gate from fan-out in the above diagram.