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Allow for suppressing warnings in NoiseModel.from_backend() #792

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merged 4 commits into from
Jun 15, 2020
Merged

Allow for suppressing warnings in NoiseModel.from_backend() #792

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10856dd
Allow for suppressing warnings in NoiseModel.from_backend()
nonhermitian Jun 11, 2020
c01394f
if warnings catch
nonhermitian Jun 12, 2020
5f2e41d
Merge branch 'master' into halt_noise_warnings
chriseclectic Jun 15, 2020
7d2f447
Merge branch 'master' into halt_noise_warnings
chriseclectic Jun 15, 2020
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27 changes: 16 additions & 11 deletions qiskit/providers/aer/noise/device/models.py
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Original file line number Diff line number Diff line change
Expand Up @@ -57,7 +57,8 @@ def basic_device_gate_errors(properties,
gate_lengths=None,
gate_length_units='ns',
temperature=0,
standard_gates=True):
standard_gates=True,
warnings=True):
"""
Return QuantumErrors derived from a devices BackendProperties.

Expand All @@ -82,6 +83,7 @@ def basic_device_gate_errors(properties,
standard_gates (bool): If true return errors as standard
qobj gates. If false return as unitary
qobj instructions (Default: True).
warnings (bool): Display warnings (Default: True).

Returns:
list: A list of tuples ``(label, qubits, QuantumError)``, for gates
Expand Down Expand Up @@ -134,7 +136,7 @@ def basic_device_gate_errors(properties,
# Get depolarizing error channel
if gate_error:
depol_error = _device_depolarizing_error(
qubits, error_param, relax_error, standard_gates)
qubits, error_param, relax_error, standard_gates, warnings=warnings)

# Combine errors
if depol_error is None and relax_error is None:
Expand All @@ -157,7 +159,8 @@ def basic_device_gate_errors(properties,
def _device_depolarizing_error(qubits,
error_param,
relax_error=None,
standard_gates=True):
standard_gates=True,
warnings=True):
"""Construct a depolarizing_error for device"""

# We now deduce the depolarizing channel error parameter in the
Expand Down Expand Up @@ -191,21 +194,23 @@ def _device_depolarizing_error(qubits,
# The minimum average gate fidelity is F_min = 1 / (dim + 1)
# So the maximum gate error is 1 - F_min = dim / (dim + 1)
if error_param > error_max:
logger.warning(
'Device reported a gate error parameter greater'
' than maximum allowed value (%f > %f). Truncating to'
' maximum value.', error_param, error_max)
if warnings:
logger.warning(
'Device reported a gate error parameter greater'
' than maximum allowed value (%f > %f). Truncating to'
' maximum value.', error_param, error_max)
error_param = error_max
# Model gate error entirely as depolarizing error
num_qubits = len(qubits)
dim = 2 ** num_qubits
depol_param = dim * (error_param - relax_infid) / (dim * relax_fid - 1)
max_param = 4**num_qubits / (4**num_qubits - 1)
if depol_param > max_param:
logger.warning(
'Device model returned a depolarizing error parameter greater'
' than maximum allowed value (%f > %f). Truncating to'
' maximum value.', depol_param, max_param)
if warnings:
logger.warning(
'Device model returned a depolarizing error parameter greater'
' than maximum allowed value (%f > %f). Truncating to'
' maximum value.', depol_param, max_param)
depol_param = min(depol_param, max_param)
return depolarizing_error(
depol_param, num_qubits, standard_gates=standard_gates)
Expand Down
11 changes: 7 additions & 4 deletions qiskit/providers/aer/noise/noise_model.py
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Original file line number Diff line number Diff line change
Expand Up @@ -179,7 +179,8 @@ def from_backend(cls, backend,
temperature=0,
gate_lengths=None,
gate_length_units='ns',
standard_gates=True):
standard_gates=True,
warnings=True):
"""Return a noise model derived from a devices backend properties.

This function generates a noise model based on:
Expand Down Expand Up @@ -259,6 +260,7 @@ def from_backend(cls, backend,
standard_gates (bool): If true return errors as standard
qobj gates. If false return as unitary
qobj instructions (Default: True)
warnings (bool): Display warnings (Default: True).

Returns:
NoiseModel: An approximate noise model for the device backend.
Expand All @@ -281,7 +283,7 @@ def from_backend(cls, backend,
# Add single-qubit readout errors
if readout_error:
for qubits, error in basic_device_readout_errors(properties):
noise_model.add_readout_error(error, qubits)
noise_model.add_readout_error(error, qubits, warnings=warnings)

# Add gate errors
gate_errors = basic_device_gate_errors(
Expand All @@ -291,9 +293,10 @@ def from_backend(cls, backend,
gate_lengths=gate_lengths,
gate_length_units=gate_length_units,
temperature=temperature,
standard_gates=standard_gates)
standard_gates=standard_gates,
warnings=warnings)
for name, qubits, error in gate_errors:
noise_model.add_quantum_error(error, name, qubits)
noise_model.add_quantum_error(error, name, qubits, warnings=warnings)
return noise_model

def __repr__(self):
Expand Down