def get_supported_channels():
"""A helper to get the channels that are supported in TFQ.
Returns a dictionary mapping from supported channel types
to number of qubits.
"""
# Add new channels here whenever additional support is needed.
channel_mapping = dict()
channel_mapping[cirq.DepolarizingChannel(0.01)] = 1
channel_mapping[cirq.AsymmetricDepolarizingChannel(0.01, 0.02, 0.03)] = 1
channel_mapping[cirq.GeneralizedAmplitudeDampingChannel(0.01, 0.02)] = 1
channel_mapping[cirq.AmplitudeDampingChannel(0.01)] = 1
channel_mapping[cirq.ResetChannel()] = 1
channel_mapping[cirq.PhaseDampingChannel(0.01)] = 1
channel_mapping[cirq.PhaseFlipChannel(0.01)] = 1
channel_mapping[cirq.BitFlipChannel(0.01)] = 1
return channel_mapping
def test_readout_error():
p00 = 0.05
p11 = 0.1
p = p11 / (p00 + p11)
gamma = p11 / p
# Create qubits and circuit
qubits = [cirq.LineQubit(0), cirq.LineQubit(1)]
circuit = cirq.Circuit(
cirq.Moment([cirq.X(qubits[0])]),
cirq.Moment([cirq.CNOT(qubits[0], qubits[1])]),
cirq.Moment([cirq.H(qubits[1])]),
cirq.Moment([
cirq.measure(qubits[0], key='q0'),
cirq.measure(qubits[1], key='q1')
]),
)
# Create noise model from NoiseProperties object with specified noise
prop = NoiseProperties(p00=p00, p11=p11)
noise_model = NoiseModelFromNoiseProperties(prop)
noisy_circuit = cirq.Circuit(noise_model.noisy_moments(circuit, qubits))
# Insert expected channels to circuit
expected_circuit = cirq.Circuit(
cirq.Moment([cirq.X(qubits[0])]),
cirq.Moment([cirq.CNOT(qubits[0], qubits[1])]),
cirq.Moment([cirq.H(qubits[1])]),
cirq.Moment([
cirq.GeneralizedAmplitudeDampingChannel(
p=p, gamma=gamma).on_each(qubits)
]),
cirq.Moment([
cirq.measure(qubits[0], key='q0'),
cirq.measure(qubits[1], key='q1')
]),
)
assert_equivalent_op_tree(expected_circuit, noisy_circuit)
# Create Noise Model with just p00
prop_p00 = NoiseProperties(p00=p00)
noise_model_p00 = NoiseModelFromNoiseProperties(prop_p00)
noisy_circuit_p00 = cirq.Circuit(
noise_model_p00.noisy_moments(circuit, qubits))
# Insert expected channels to circuit
expected_circuit_p00 = cirq.Circuit(
cirq.Moment([cirq.X(qubits[0])]),
cirq.Moment([cirq.CNOT(qubits[0], qubits[1])]),
cirq.Moment([cirq.H(qubits[1])]),
cirq.Moment([
cirq.GeneralizedAmplitudeDampingChannel(p=0.0,
gamma=p00).on_each(qubits)
]),
cirq.Moment([
cirq.measure(qubits[0], key='q0'),
cirq.measure(qubits[1], key='q1')
]),
)
assert_equivalent_op_tree(expected_circuit_p00, noisy_circuit_p00)
# Create Noise Model with just p11
prop_p11 = NoiseProperties(p11=p11)
noise_model_p11 = NoiseModelFromNoiseProperties(prop_p11)
noisy_circuit_p11 = cirq.Circuit(
noise_model_p11.noisy_moments(circuit, qubits))
# Insert expected channels to circuit
expected_circuit_p11 = cirq.Circuit(
cirq.Moment([cirq.X(qubits[0])]),
cirq.Moment([cirq.CNOT(qubits[0], qubits[1])]),
cirq.Moment([cirq.H(qubits[1])]),
cirq.Moment([
cirq.GeneralizedAmplitudeDampingChannel(p=1.0,
gamma=p11).on_each(qubits)
]),
cirq.Moment([
cirq.measure(qubits[0], key='q0'),
cirq.measure(qubits[1], key='q1')
]),
)
assert_equivalent_op_tree(expected_circuit_p11, noisy_circuit_p11)
def test_combined_error():
# Helper function to calculate pauli error from depolarization
def pauli_error_from_depolarization(pauli_error, t1_ns, duration):
t2 = 2 * t1_ns
pauli_error_from_t1 = (1 - np.exp(-duration / t2)) / 2 + (
1 - np.exp(-duration / t1_ns)) / 4
if pauli_error >= pauli_error_from_t1:
return pauli_error - pauli_error_from_t1
return pauli_error
t1_ns = 2000.0
p11 = 0.01
# Account for floating point errors
# Needs Cirq issue 3965 to be resolved
pauli_error = 0.019999999999999962
# Create qubits and circuit
qubits = [cirq.LineQubit(0), cirq.LineQubit(1)]
circuit = cirq.Circuit(
cirq.Moment([cirq.X(qubits[0])]),
cirq.Moment([cirq.CNOT(qubits[0], qubits[1])]),
cirq.Moment([cirq.measure(qubits[0], key='q0')]),
cirq.Moment([cirq.ISwapPowGate().on_each(qubits)]),
cirq.Moment([
cirq.measure(qubits[0], key='q0'),
cirq.measure(qubits[1], key='q1')
]),
)
# Create noise model from NoiseProperties object with specified noise
prop = NoiseProperties(t1_ns=t1_ns, p11=p11, pauli_error=pauli_error)
noise_model = NoiseModelFromNoiseProperties(prop)
with pytest.warns(
RuntimeWarning,
match='Pauli error from T1 decay is greater than total Pauli error'
):
noisy_circuit = cirq.Circuit(noise_model.noisy_moments(
circuit, qubits))
# Insert expected channels to circuit
expected_circuit = cirq.Circuit(
cirq.Moment([cirq.X(qubits[0])]),
cirq.Moment([
cirq.depolarize(
pauli_error_from_depolarization(pauli_error, t1_ns, 25.0) /
3).on_each(qubits)
]),
cirq.Moment(
[cirq.amplitude_damp(1 - np.exp(-25.0 / t1_ns)).on_each(qubits)]),
cirq.Moment([cirq.CNOT(qubits[0], qubits[1])]),
cirq.Moment([
cirq.depolarize(
pauli_error_from_depolarization(pauli_error, t1_ns, 25.0) /
3).on_each(qubits)
]),
cirq.Moment(
[cirq.amplitude_damp(1 - np.exp(-25.0 / t1_ns)).on_each(qubits)]),
cirq.Moment([
cirq.GeneralizedAmplitudeDampingChannel(p=1.0,
gamma=p11).on(qubits[0])
]),
cirq.Moment([cirq.measure(qubits[0], key='q0')]),
cirq.Moment([
cirq.depolarize(
pauli_error_from_depolarization(pauli_error, t1_ns, 4000.0) /
3).on_each(qubits)
]),
cirq.Moment([
cirq.amplitude_damp(1 - np.exp(-4000.0 / t1_ns)).on_each(qubits)
]),
cirq.Moment([cirq.ISwapPowGate().on_each(qubits)]),
cirq.Moment([
cirq.depolarize(
pauli_error_from_depolarization(pauli_error, t1_ns, 32.0) /
3).on_each(qubits)
]),
cirq.Moment(
[cirq.amplitude_damp(1 - np.exp(-32.0 / t1_ns)).on_each(qubits)]),
cirq.Moment([
cirq.GeneralizedAmplitudeDampingChannel(p=1.0,
gamma=p11).on_each(qubits)
]),
cirq.Moment([
cirq.measure(qubits[0], key='q0'),
cirq.measure(qubits[1], key='q1')
]),
cirq.Moment([
cirq.depolarize(
pauli_error_from_depolarization(pauli_error, t1_ns, 4000.0) /
3).on_each(qubits)
]),
cirq.Moment([
cirq.amplitude_damp(1 - np.exp(-4000.0 / t1_ns)).on_each(qubits)
]),
)
assert_equivalent_op_tree(expected_circuit, noisy_circuit)
def test_generalized_amplitude_damping_repr():
cirq.testing.assert_equivalent_repr(
cirq.GeneralizedAmplitudeDampingChannel(0.1, 0.3))
cirq.MutableDensePauliString('XXZZ', coefficient=-2),
'FREDKIN':
cirq.FREDKIN,
'FSimGate':
cirq.FSimGate(theta=0.123, phi=.456),
'Foxtail':
cirq.google.Foxtail,
'GateOperation': [
cirq.CCNOT(*cirq.LineQubit.range(3)),
cirq.CCZ(*cirq.LineQubit.range(3)),
cirq.CNOT(*cirq.LineQubit.range(2)),
cirq.CSWAP(*cirq.LineQubit.range(3)),
cirq.CZ(*cirq.LineQubit.range(2))
],
'GeneralizedAmplitudeDampingChannel':
cirq.GeneralizedAmplitudeDampingChannel(0.1, 0.2),
'GlobalPhaseOperation':
cirq.GlobalPhaseOperation(-1j),
'GridQubit':
cirq.GridQubit(10, 11),
'H':
cirq.H,
'HPowGate': [cirq.HPowGate(exponent=-8), cirq.H**0.123],
'I':
cirq.I,
'ISWAP':
cirq.ISWAP,
'ISwapPowGate': [cirq.ISwapPowGate(exponent=-8), cirq.ISWAP**0.123],
'IdentityGate': [
cirq.I,
cirq.IdentityGate(num_qubits=5),
