Five two-bit quantum gates are sufficient to implement the quantum Fredkin gate
John A. Smolin, David Peter Divincenzo · Physical Review A · 1996
We present an analytic construction of the three-bit quantum conditional swap (Fredkin) gate that uses only five quantum gates, each acting on only two qubits. Our implementation is based on previous work on the three-bit quantum conditional-NOT (Toffoli) gate. Numerical evidence suggests that this is a minimal implementation. \textcopyright{} 1996 The American Physical Society.