Logic Gates as Functions

A logic gate is just a deterministic function: the same inputs always produce the same output. NOT is a function of one bit; AND, OR, and XOR are functions of two bits. Thinking of gates as functions is the right mindset for quantum gates too — except quantum gates are functions that must be reversible and act on amplitudes, not just bits.

XOR (exclusive or, written $\oplus$) outputs 1 exactly when its inputs differ: $0\oplus0=0$, $0\oplus1=1$, $1\oplus0=1$, $1\oplus1=0$. It is the classical cousin of the quantum CNOT gate you will meet later.

Try it

Return $1 \oplus 0$ (use JavaScript's ^ operator).

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