Efficient construction of three- and four-qubit quantum gates by global entangling gates
Efficient construction of three- and four-qubit quantum gates by global entangling gates
We present improved circuits for the Toffoli gate and the control-swap (Fredkin) gate using three and four global two-qubit gates, respectively. This is a nearly double speedup compared to the conventional circuits, which require five (for Toffoli) and seven (for Fredkin) local two-qubit gates. We apply the same approach to …