qiskit-aer/qiskit_aer/utils/noise_model_inserter.py

67 lines
2.9 KiB
Python

# This code is part of Qiskit.
#
# (C) Copyright IBM 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.
"""
Noise model inserter module
The goal of this module is to add QuantumError gates (Kraus gates) to a circuit
based on a given noise model.
"""
import qiskit.compiler
def insert_noise(circuits, noise_model, transpile=False):
"""Return a noisy version of a QuantumCircuit.
Args:
circuits (QuantumCircuit or list[QuantumCircuit]): Input noise-free circuits.
noise_model (NoiseModel): The noise model containing the errors to add
transpile (Boolean): Should the circuit be transpiled into the noise model basis gates
Returns:
QuantumCircuit: The new circuit with the Kraus noise instructions inserted.
Additional Information:
The noisy circuit return by this function will consist of the
original circuit with ``Kraus`` instructions inserted after all
instructions referenced in the ``noise_model``. The resulting circuit
cannot be ran on a quantum computer but can be executed on the
:class:`~qiskit_aer.QasmSimulator`.
"""
is_circuits_list = isinstance(circuits, (list, tuple))
circuits = circuits if is_circuits_list else [circuits]
result_circuits = []
local_errors = noise_model._local_quantum_errors
default_errors = noise_model._default_quantum_errors
for circuit in circuits:
if transpile:
transpiled_circuit = qiskit.compiler.transpile(
circuit, basis_gates=noise_model.basis_gates
)
else:
transpiled_circuit = circuit
qubit_indices = {bit: index for index, bit in enumerate(transpiled_circuit.qubits)}
result_circuit = transpiled_circuit.copy(name=transpiled_circuit.name + "_with_noise")
result_circuit.data = []
for inst in transpiled_circuit.data:
result_circuit.data.append(inst)
qubits = tuple(qubit_indices[q] for q in inst.qubits)
# Priority for error model used:
# local error > default error
name = inst.operation.name
if name in local_errors and qubits in local_errors[name]:
error = local_errors[name][qubits]
result_circuit.append(error.to_instruction(), inst.qubits)
elif name in default_errors.keys():
error = default_errors[name]
result_circuit.append(error.to_instruction(), inst.qubits)
result_circuits.append(result_circuit)
return result_circuits if is_circuits_list else result_circuits[0]