def test_find_optimal_representation_no_superoperator_error():
q = LineQubit(0)
# Define noisy operation without superoperator matrix
noisy_op = NoisyOperation(Circuit(X(q)))
noisy_basis = NoisyBasis(noisy_op)
with raises(ValueError, match="numerical superoperator matrix"):
find_optimal_representation(Circuit(X(q)), noisy_basis)
def test_find_optimal_representation_depolarizing_two_qubit_gates(circ_type):
"""Test optimal representation agrees with a known analytic result."""
for ideal_gate, noise_level in product([CNOT, CZ], [0.1, 0.5]):
q = LineQubit.range(2)
ideal_op = Circuit(ideal_gate(*q))
implementable_circuits = [Circuit(ideal_op)]
# Append two-qubit-gate with Paulis on one qubit
for gate in [X, Y, Z]:
implementable_circuits.append(Circuit([ideal_op, gate(q[0])]))
implementable_circuits.append(Circuit([ideal_op, gate(q[1])]))
# Append two-qubit gate with Paulis on both qubits
for gate_a, gate_b in product([X, Y, Z], repeat=2):
implementable_circuits.append(
Circuit([ideal_op, gate_a(q[0]), gate_b(q[1])])
)
noisy_circuits = [
circ + Circuit(DepolarizingChannel(noise_level).on_each(*q))
for circ in implementable_circuits
]
super_operators = [
choi_to_super(_circuit_to_choi(circ)) for circ in noisy_circuits
]
# Define circuits with native types
implementable_native = [
convert_from_mitiq(c, circ_type) for c in implementable_circuits
]
ideal_op_native = convert_from_mitiq(ideal_op, circ_type)
noisy_operations = [
NoisyOperation(ideal, real)
for ideal, real in zip(implementable_native, super_operators)
]
# Find optimal representation
noisy_basis = NoisyBasis(*noisy_operations)
rep = find_optimal_representation(
ideal_op_native, noisy_basis, tol=1.0e-8
)
# Expected analytical result
expected_rep = represent_operation_with_local_depolarizing_noise(
ideal_op_native,
noise_level,
)
assert np.allclose(np.sort(rep.coeffs), np.sort(expected_rep.coeffs))
assert rep == expected_rep
def test_find_optimal_representation_single_qubit_amp_damping(circ_type):
"""Test optimal representation of agrees with a known analytic result."""
for ideal_gate, noise_level in product([X, Y, H], [0.1, 0.3]):
q = LineQubit(0)
ideal_op = Circuit(ideal_gate(q))
implementable_circuits = [Circuit(ideal_op)]
# Add ideal gate followed by Paulis and reset
for gate in [Z, reset]:
implementable_circuits.append(Circuit([ideal_op, gate(q)]))
noisy_circuits = [
circ + Circuit(AmplitudeDampingChannel(noise_level).on_each(q))
for circ in implementable_circuits
]
super_operators = [
choi_to_super(_circuit_to_choi(circ)) for circ in noisy_circuits
]
# Define circuits with native types
implementable_native = [
convert_from_mitiq(c, circ_type) for c in implementable_circuits
]
ideal_op_native = convert_from_mitiq(ideal_op, circ_type)
noisy_operations = [
NoisyOperation(ideal, real)
for ideal, real in zip(implementable_native, super_operators)
]
# Find optimal representation
noisy_basis = NoisyBasis(*noisy_operations)
rep = find_optimal_representation(
ideal_op_native, noisy_basis, tol=1.0e-7, initial_guess=[0, 0, 0]
)
# Expected analytical result
expected_rep = _represent_operation_with_amplitude_damping_noise(
ideal_op_native,
noise_level,
)
assert np.allclose(np.sort(rep.coeffs), np.sort(expected_rep.coeffs))
assert rep == expected_rep
