qit.gate.controlled

qit.gate.controlled(U, ctrl=(1,), dim=None)

Controlled gate.

Parameters

  • U (array[complex], Lmap) – unitary operator

  • ctrl (vector[int]) – control nodes

  • dim (tuple[int]) – control subsystem dimensions

Returns

controlled-U gate

Return type

Lmap

Returns the (t+1)-qudit controlled-U gate, where t == len(ctrl).

ctrl defines the control nodes. It has one entry k per control qudit, denoting the required computational basis state \(\ket{k}\) for that particular qudit. Value k == -1 denotes no control.

dim is the dimensions vector for the control qudits. If not given, all controls are assumed to be qubits.

Examples

  • controlled(NOT, [1]) gives the standard CNOT gate.

  • controlled(NOT, [1, 1]) gives the Toffoli gate.