# This code is part of Qiskit.
#
# (C) Copyright IBM 2018, 2019.
#
# This code is licensed under the Apache License, Version 2.0. You may
# obtain a copy of this license in the LICENSE.txt file in the root directory
# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
#
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
# that they have been altered from the originals.
"""
Functions to extract device error parameters from backend properties.
"""
from numpy import inf
# Time and frequency unit conversions
_NANOSECOND_UNITS = {"s": 1e9, "ms": 1e6, "µs": 1e3, "us": 1e3, "ns": 1}
_GHZ_UNITS = {"Hz": 1e-9, "KHz": 1e-6, "MHz": 1e-3, "GHz": 1, "THz": 1e3}
[docs]def gate_param_values(properties):
"""
Return parameter error values from a devices BackendProperties.
Args:
properties (BackendProperties): device backend properties
Returns:
list: A list of tuples ``(name, qubits, time, error)``. If gate
error or gate_length information is not available ``None``
will be returned for value.
"""
values = []
for gate in properties.gates:
name = gate.gate
qubits = gate.qubits
# Check for gate time information
gate_length = None # default value
time_param = _check_for_item(gate.parameters, "gate_length")
if hasattr(time_param, "value"):
gate_length = time_param.value
if hasattr(time_param, "unit"):
# Convert gate time to ns
gate_length *= _NANOSECOND_UNITS.get(time_param.unit, 1)
# Check for gate error information
gate_error = None # default value
error_param = _check_for_item(gate.parameters, "gate_error")
if hasattr(error_param, "value"):
gate_error = error_param.value
values.append((name, qubits, gate_length, gate_error))
return values
[docs]def gate_error_values(properties):
"""
Return gate error values from a devices BackendProperties.
Args:
properties (BackendProperties): device backend properties
Returns:
list: A list of tuples ``(name, qubits, value)``. If gate
error information is not available ``None`` will be returned
for value.
"""
values = []
for gate in properties.gates:
name = gate.gate
qubits = gate.qubits
value = None # default value
params = _check_for_item(gate.parameters, "gate_error")
if hasattr(params, "value"):
value = params.value
values.append((name, qubits, value))
return values
[docs]def gate_length_values(properties):
"""
Return gate length values from a devices BackendProperties.
Args:
properties (BackendProperties): device backend properties
Returns:
list: A list of tuples ``(name, qubits, value)``. If gate length
information is not available ``None`` will be returned for value.
Additional Information:
Gate length values are returned in nanosecond (ns) units.
"""
values = []
for gate in properties.gates:
name = gate.gate
qubits = gate.qubits
value = None # default value
params = _check_for_item(gate.parameters, "gate_length")
if hasattr(params, "value"):
value = params.value
if hasattr(params, "unit"):
# Convert gate time to ns
value *= _NANOSECOND_UNITS.get(params.unit, 1)
values.append((name, qubits, value))
return values
[docs]def readout_error_values(properties):
"""
Return readout error values from a devices BackendProperties.
Args:
properties (BackendProperties): device backend properties
Returns:
list: A list of readout error values for qubits. If readout
error information is not available None will be returned
for value.
"""
values = []
for qubit_props in properties.qubits:
value = None # default value
params_roerror = _check_for_item(qubit_props, "readout_error")
params_m1p0 = _check_for_item(qubit_props, "prob_meas1_prep0")
params_m0p1 = _check_for_item(qubit_props, "prob_meas0_prep1")
if hasattr(params_m1p0, "value") and hasattr(params_m0p1, "value"):
value = [params_m1p0.value, params_m0p1.value]
elif hasattr(params_roerror, "value"):
value = [params_roerror.value, params_roerror.value]
values.append(value)
return values
[docs]def thermal_relaxation_values(properties):
"""
Return T1, T2 and frequency values from a devices BackendProperties.
Args:
properties (BackendProperties): device backend properties
Returns:
list: A list of tuples ``(T1, T2, freq)`` for each qubit in the device.
If :math:`T_1`, :math:`T_2`, or frequency cannot be found for qubit a
value of ``Numpy.inf`` will be used.
Additional Information:
:math:`T_1` and :math:`T_2` values are returned in nanosecond
(ns) units and frequency is returned in gigahertz (GHz) units
if ``unit`` for each ``value`` is provided in ``properties``.
Otherwise, the raw values (in unknown original units) are returned.
"""
values = []
for qubit_props in properties.qubits:
# pylint: disable=invalid-name
# Default values
t1, t2, freq = inf, inf, inf
# Get the readout error value
t1_params = _check_for_item(qubit_props, "T1")
t2_params = _check_for_item(qubit_props, "T2")
freq_params = _check_for_item(qubit_props, "frequency")
# Load values from parameters
if hasattr(t1_params, "value"):
t1 = t1_params.value
if hasattr(t1_params, "unit"):
# Convert to nanoseconds
t1 *= _NANOSECOND_UNITS.get(t1_params.unit, 1)
if hasattr(t2_params, "value"):
t2 = t2_params.value
if hasattr(t2_params, "unit"):
# Convert to nanoseconds
t2 *= _NANOSECOND_UNITS.get(t2_params.unit, 1)
if hasattr(freq_params, "value"):
freq = freq_params.value
if hasattr(freq_params, "unit"):
# Convert to Gigahertz
freq *= _GHZ_UNITS.get(freq_params.unit, 1)
values.append((t1, t2, freq))
return values
def _check_for_item(lst, name):
"""Search list for item with given name."""
filtered = [item for item in lst if item.name == name]
if not filtered:
return None
else:
return filtered[0]