Chapter 3 Quantum gates
About understanding the square root of
\texttt{NOT} via a physical implementation using symmetric beam-splitters. More about the Bloch sphere, via the omnipresent Pauli matrices, which can be described in a more algebraic way.
Before introducing too many new ideas, we first want to study two things we’ve already seen in more depth, namely the square root of
The goal for the latter is to be able to visualise sequences of unitary operations on a qubit as sequences of rotations, and to see the action of some quantum circuits without getting engaged in lengthy calculations; this also leads us back to the question of universal sets of gates. The goal for the former is to study a way of implementing this gate using physical experiments, and then studying a related construction (the so-called Mach–Zehnder interferometer).