def _dec_mcg_up_diag(self):
"""
Call to create a circuit with gates that implement the MCG up to a diagonal gate.
Remark: The qubits the gate acts on are ordered in the following way:
q=[q_target,q_controls,q_ancilla_zero,q_ancilla_dirty]
"""
diag = np.ones(2 ** (self.num_controls + 1)).tolist()
q = QuantumRegister(self.num_qubits)
circuit = QuantumCircuit(q)
(q_target, q_controls, q_ancillas_zero, q_ancillas_dirty) = self._define_qubit_role(q)
# ToDo: Keep this threshold updated such that the lowest gate count is achieved:
# ToDo: we implement the MCG with a UCG up to diagonal if the number of controls is
# ToDo: smaller than the threshold.
threshold = float("inf")
if self.num_controls < threshold:
# Implement the MCG as a UCG (up to diagonal)
gate_list = [np.eye(2, 2) for i in range(2 ** self.num_controls)]
gate_list[-1] = self.params[0]
ucg = UCG(gate_list, up_to_diagonal=True)
circuit.append(ucg, [q_target] + q_controls)
diag = ucg._get_diagonal()
# else:
# ToDo: Use the best decomposition for MCGs up to diagonal gates here
# ToDo: (with all available ancillas)
return circuit, diag
def _append_ucg_up_to_diagonal(self, circ, q, single_qubit_gates,
control_labels, target_label):
(q_input, q_ancillas_for_output, q_ancillas_zero, q_ancillas_dirty) = \
self._define_qubit_role(q)
n = int(np.log2(self.params[0].shape[0]))
qubits = q_input + q_ancillas_for_output
# Note that we have to reverse the control labels, since controls are provided by
# increasing qubit number toa UCG by convention
control_qubits = _reverse_qubit_oder(
_get_qubits_by_label(control_labels, qubits, n))
target_qubit = _get_qubits_by_label([target_label], qubits, n)[0]
ucg = UCG(single_qubit_gates, up_to_diagonal=True)
circ.append(ucg, [target_qubit] + control_qubits)
return ucg._get_diagonal()
def test_ucg(self):
"""Test uniformly controlled gates."""
for squs, up_to_diagonal in itertools.product(squs_list,
up_to_diagonal_list):
with self.subTest(single_qubit_unitaries=squs,
up_to_diagonal=up_to_diagonal):
num_con = int(np.log2(len(squs)))
q = QuantumRegister(num_con + 1)
qc = QuantumCircuit(q)
qc.ucg(squs, q[1:], q[0], up_to_diagonal=up_to_diagonal)
# Decompose the gate
qc = transpile(qc, basis_gates=['u1', 'u3', 'u2', 'cx', 'id'])
# Simulate the decomposed gate
simulator = BasicAer.get_backend('unitary_simulator')
result = execute(qc, simulator).result()
unitary = result.get_unitary(qc)
if up_to_diagonal:
ucg = UCG(squs, up_to_diagonal=up_to_diagonal)
unitary = np.dot(np.diagflat(ucg._get_diagonal()), unitary)
unitary_desired = _get_ucg_matrix(squs)
self.assertTrue(
matrix_equal(unitary_desired, unitary, ignore_phase=True))