I Help in understanding a quantum circuit

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1. Mar 29, 2017

victor94

I'm in a proyect to simulate quantum circuits in robots like in this paper
( http://ieeexplore.ieee.org/document/4215941/ ) ,the first thing that i need to do is to simulated the circuit that is in that paper:

But i'm having trouble understanding how the hadamard gate affects the "C" entrance, any help will be appreciated.

Thanks

2. Mar 30, 2017

Strilanc

In this case, assuming $S1$ is off or on (i.e. not in a superposition w.r.t. the computational basis), the Hadamard gate just acts like a classical coin flip because its output is only ever measured or used to control other operations.

$S2$ seems completely pointless as far as I can tell.

You can simulate the circuit in Quirk to see the specific cases: