# NoiseModel¶

class NoiseModel(basis_gates=None)[source]

Noise model class for Qiskit Aer simulators.

This class is used to represent noise model for the QasmSimulator. It can be used to construct custom noise models for simulator, or to automatically generate a basic device noise model for an IBMQ backend. See the noise module documentation for additional information.

Example: Basic device noise model

An approximate NoiseModel can be generated automatically from the properties of real device backends from the IBMQ provider using the from_backend() method.

from qiskit import IBMQ, Aer
from qiskit.providers.aer.noise import NoiseModel

provider = IBMQ.load_account()
backend = provider.get_backend('ibmq_vigo')
noise_model = NoiseModel.from_backend(backend)
print(noise_model)


Example: Custom noise model

Custom noise models can be used by adding QuantumError to circuit gate, reset or measure instructions, and ReadoutError to measure instructions.

import qiskit.providers.aer.noise as noise

# Error probabilities
prob_1 = 0.001  # 1-qubit gate
prob_2 = 0.01   # 2-qubit gate

# Depolarizing quantum errors
error_1 = noise.depolarizing_error(prob_1, 1)
error_2 = noise.depolarizing_error(prob_2, 2)

# Add errors to noise model
noise_model = noise.NoiseModel()
noise_model.add_all_qubit_quantum_error(error_1, ['u1', 'u2', 'u3'])
noise_model.add_all_qubit_quantum_error(error_2, ['cx'])
print(noise_model)


Initialize an empty noise model.

Parameters

basis_gates (list[str] or None) – Specify an initial basis_gates for the noise model. If None a default value of [‘id’, ‘u3’, ‘cx’] is used (Default: None).

Additional Information: Errors added to the noise model will have their instruction appended to the noise model basis_gates if the instruction is in the QasmSimulator basis_gates. If the instruction is not in the QasmSimulator basis_gates it is assumed to be a label for a standard gate, and that gate should be added to the NoiseModel basis_gates either using the init method, or the add_basis_gates() method.

Attributes

 NoiseModel.basis_gates Return basis_gates for compiling to the noise model. NoiseModel.noise_instructions Return the set of noisy instructions for this noise model. NoiseModel.noise_qubits Return the set of noisy qubits for this noise model.

Methods

 Add a quantum error to the noise model that applies to all qubits. Add a single-qubit readout error that applies measure on all qubits. NoiseModel.add_basis_gates(instructions[, …]) Add additional gates to the noise model basis_gates. Add a non-local quantum error to the noise model. NoiseModel.add_quantum_error(error, …[, …]) Add a quantum error to the noise model. NoiseModel.add_readout_error(error, qubits) Add a readout error to the noise model. NoiseModel.from_backend(backend[, …]) Return a noise model derived from a devices backend properties. NoiseModel.from_dict(noise_dict) Load NoiseModel from a dictionary. Return True if the noise model has no noise terms. Reset the noise model. Declares X90 based gates for noise model. NoiseModel.to_dict([serializable]) Return the noise model as a dictionary.