Quantum Computing: Grover's Algorithm — Inversion About the Mean

Originally published on malcolmlow.net Grover's algorithm is a quantum search procedure that locates a marked item in an unsorted list of N items in O(√N) oracle queries — a quadratic speedup over any classical approach. For N = 8 (3 qubits), this means roughly ⌊π/4 × √8⌋ = 2 optimal iterations before the probability of measuring the target state peaks. This walkthrough tracks the exact amplitude of every basis state through each gate operation for the 3-qubit case, with target state |101⟩ . All