def control(self, num_ctrl_qubits=1, label=None, ctrl_state=None):
r"""Return controlled version of gate
Args:
num_ctrl_qubits (int): number of controls to add to gate (default=1)
label (str): optional gate label
ctrl_state (int or str or None): The control state in decimal or as a
bit string (e.g. '1011'). If None, use 2**num_ctrl_qubits-1.
Returns:
UnitaryGate: controlled version of gate.
Raises:
QiskitError: invalid ctrl_state
"""
cmat = _compute_control_matrix(self.to_matrix(), num_ctrl_qubits)
iso = isometry.Isometry(cmat, 0, 0)
cunitary = ControlledGate('c-unitary',
self.num_qubits + num_ctrl_qubits,
cmat,
definition=iso.definition,
label=label)
cunitary.base_gate = self.copy()
cunitary.base_gate.label = self.label
return cunitary
def control(self, num_ctrl_qubits=1, label=None, ctrl_state=None):
r"""Return controlled version of gate
Args:
num_ctrl_qubits (int): number of controls to add to gate (default=1)
label (str): optional gate label
ctrl_state (int or str or None): The control state in decimal or as a
bit string (e.g. '1011'). If None, use 2**num_ctrl_qubits-1.
Returns:
UnitaryGate: controlled version of gate.
Raises:
QiskitError: Invalid ctrl_state.
ExtensionError: Non-unitary controlled unitary.
"""
cmat = _compute_control_matrix(self.to_matrix(),
num_ctrl_qubits,
ctrl_state=ctrl_state)
iso = isometry.Isometry(cmat, 0, 0)
cunitary = ControlledGate('c-unitary',
num_qubits=self.num_qubits + num_ctrl_qubits,
params=[cmat],
label=label,
num_ctrl_qubits=num_ctrl_qubits,
definition=iso.definition,
ctrl_state=ctrl_state)
from qiskit.quantum_info import Operator
# hack to correct global phase; should fix to prevent need for correction here
pmat = (Operator(iso.inverse()).data @ cmat)
diag = numpy.diag(pmat)
if not numpy.allclose(diag, diag[0]):
raise ExtensionError('controlled unitary generation failed')
phase = numpy.angle(diag[0])
if phase:
qreg = cunitary.definition.qregs[0]
cunitary.definition.u3(numpy.pi, phase, phase - numpy.pi, qreg[0])
cunitary.definition.u3(numpy.pi, 0, numpy.pi, qreg[0])
cunitary.base_gate = self.copy()
cunitary.base_gate.label = self.label
return cunitary
