The Simplest Way to Compare Single-Qubit Quantum States

Learning the quantum algorithm for state overlap” by Lukasz Cincio, Yiğit Subaşı, Andrew T. Sornborger, and Patrick J. Coles proposes a simplified circuit for comparing single-qubit quantum states as compared to the canonical SWAP Test. Whereas the SWAP Test requires two Hadamard gates, one Fredkin gate, and one measurement, this paper proposes using only one CNOT gate, one Hadamard gate, and…