When More Becomes Less: Topology-Reversed Three-Qubit Gate Performance on IBM Quantum Processors

Simona K. Grigorova, Stancho S. Stanchev, Nikolay V. Vitanov

The exact Toffoli gate admits a six-CX decomposition, denoted by $CC{X}_6$, that is optimal under unrestricted two-qubit connectivity. On a linear three-qubit topology, however, $CCX…