Código fuente para qiskit_machine_learning.circuit.library.qnn_circuit

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# (C) Copyright IBM 2023.
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"""The QNN circuit."""
from __future__ import annotations
from typing import List
from qiskit.circuit import QuantumRegister, QuantumCircuit
from qiskit.circuit.parametertable import ParameterView
from qiskit.circuit.library import BlueprintCircuit
from qiskit_machine_learning.utils import derive_num_qubits_feature_map_ansatz
from qiskit_machine_learning import QiskitMachineLearningError


[documentos]class QNNCircuit(BlueprintCircuit): """ The QNN circuit is a blueprint circuit that wraps feature map and ansatz circuits. It can be used to simplify the composition of these two. If only the number of qubits is provided the :class:`~qiskit.circuit.library.RealAmplitudes` ansatz and the :class:`~qiskit.circuit.library.ZZFeatureMap` feature map are used. If the number of qubits is 1 the :class:`~qiskit.circuit.library.ZFeatureMap` is used. If only a feature map is provided, the :class:`~qiskit.circuit.library.RealAmplitudes` ansatz with the corresponding number of qubits is used. If only an ansatz is provided the :class:`~qiskit.circuit.library.ZZFeatureMap` with the corresponding number of qubits is used. At least one parameter has to be provided. If a feature map and an ansatz is provided, the number of qubits must be the same. In case number of qubits is provided along with either a feature map, an ansatz or both, a potential mismatch between the three inputs with respect to the number of qubits is resolved by constructing the :class:`~qiskit_machine_learning.circuit.library.QNNCircuit` with the given number of qubits. If one of the :class:`~qiskit_machine_learning.circuit.library.QNNCircuit` properties is set after the class construction, the circuit is adjusted to incorporate the changes. This means, a new valid configuration that considers the latest property update will be derived. This ensures that the classes properties are consistent at all times. Example: .. code-block:: python from qiskit_machine_learning.circuit.library import QNNCircuit qnn_qc = QNNCircuit(2) print(qnn_qc) # prints: # ┌──────────────────────────┐» # q_0: ┤0 ├» # │ ZZFeatureMap(x[0],x[1]) │» # q_1: ┤1 ├» # └──────────────────────────┘» # « ┌──────────────────────────────────────────────────────────┐ # «q_0: ┤0 ├ # « │ RealAmplitudes(θ[0],θ[1],θ[2],θ[3],θ[4],θ[5],θ[6],θ[7]) │ # «q_1: ┤1 ├ # « └──────────────────────────────────────────────────────────┘ print(qnn_qc.num_qubits) # prints: 2 print(qnn_qc.input_parameters) # prints: ParameterView([ParameterVectorElement(x[0]), ParameterVectorElement(x[1])]) print(qnn_qc.weight_parameters) # prints: ParameterView([ParameterVectorElement(θ[0]), ParameterVectorElement(θ[1]), # ParameterVectorElement(θ[2]), ParameterVectorElement(θ[3]), # ParameterVectorElement(θ[4]), ParameterVectorElement(θ[5]), # ParameterVectorElement(θ[6]), ParameterVectorElement(θ[7])]) """ def __init__( self, num_qubits: int | None = None, feature_map: QuantumCircuit | None = None, ansatz: QuantumCircuit | None = None, ) -> None: """ Although all parameters default to None at least one parameter must be provided, to determine the number of qubits from it, when the instance is created. If more than one parameter is passed: 1) If num_qubits is provided the feature map and/or ansatz supplied will be overridden to circuits with num_qubits, as long as the respective circuit supports updating its number of qubits. 2) If num_qubits is not provided the feature_map and ansatz must be set to the same number of qubits. Args: num_qubits: Number of qubits, a positive integer. Optional if feature_map or ansatz is provided, otherwise required. If not provided num_qubits defaults from the sizes of feature_map and ansatz. feature_map: A feature map. Optional if num_qubits or ansatz is provided, otherwise required. If not provided defaults to :class:`~qiskit.circuit.library.ZZFeatureMap` or :class:`~qiskit.circuit.library.ZFeatureMap` if num_qubits is determined to be 1. ansatz: An ansatz. Optional if num_qubits or feature_map is provided, otherwise required. If not provided defaults to :class:`~qiskit.circuit.library.RealAmplitudes`. Returns: The composed feature map and ansatz circuit. Raises: QiskitMachineLearningError: If a valid number of qubits cannot be derived from the \ provided input arguments. """ super().__init__() self._feature_map = feature_map self._ansatz = ansatz # Check if circuit is constructed with valid configuration and set properties accordingly. self.num_qubits, self._feature_map, self._ansatz = derive_num_qubits_feature_map_ansatz( num_qubits, feature_map, ansatz ) def _build(self): super()._build() self.compose(self.feature_map, inplace=True) self.compose(self.ansatz, inplace=True) def _check_configuration(self, raise_on_failure=True): try: self.num_qubits, self.feature_map, self.ansatz = derive_num_qubits_feature_map_ansatz( self.num_qubits, self.feature_map, self.ansatz ) except QiskitMachineLearningError as qml_ex: if raise_on_failure: raise qml_ex @property def num_qubits(self) -> int: """Returns the number of qubits in this circuit. Returns: The number of qubits. """ return super().num_qubits @num_qubits.setter def num_qubits(self, num_qubits: int) -> None: """Set the number of qubits. If num_qubits is set the feature map and ansatz are adjusted to circuits with num_qubits qubits. Args: num_qubits: The number of qubits, a positive integer. """ if self.num_qubits != num_qubits: # invalidate the circuit self._invalidate() self.qregs: List[QuantumRegister] = [] if num_qubits is not None and num_qubits > 0: self.qregs = [QuantumRegister(num_qubits, name="q")] ( self.num_qubits, self._feature_map, self._ansatz, ) = derive_num_qubits_feature_map_ansatz( num_qubits, self._feature_map, self._ansatz ) @property def feature_map(self) -> QuantumCircuit: """Returns feature_map. Returns: The feature map. """ return self._feature_map @feature_map.setter def feature_map(self, feature_map: QuantumCircuit) -> None: """Set the feature map. If the feature map is updated the ``QNNCircuit`` is adjusted according to the feature map being passed. This includes: 1) The num_qubits is adjusted to the feature map number of qubits. 2) The ansatz is adjusted to a circuit with the feature_map number of qubits. Args: feature_map: The feature map. """ if self.feature_map != feature_map: # invalidate the circuit self._invalidate() self.num_qubits = feature_map.num_qubits self.num_qubits, self._feature_map, self._ansatz = derive_num_qubits_feature_map_ansatz( self.num_qubits, feature_map, self.ansatz ) @property def ansatz(self) -> QuantumCircuit: """Returns ansatz. Returns: The ansatz. """ return self._ansatz @ansatz.setter def ansatz(self, ansatz: QuantumCircuit) -> None: """Set the ansatz. If the ansatz is updated the ``QNNCircuit`` is adapted according to the ansatz being passed. This includes: 1) The num_qubits is adjusted to the ansatz number of qubits. 2) The feature_map is adjusted to a circuit with the ansatz number of qubits. Args: ansatz: The ansatz. """ if self.ansatz != ansatz: # invalidate the circuit self._invalidate() self.num_qubits = ansatz.num_qubits self.num_qubits, self._feature_map, self._ansatz = derive_num_qubits_feature_map_ansatz( self.num_qubits, self.feature_map, ansatz ) @property def input_parameters(self) -> ParameterView: """Returns the parameters of the feature map. Returns: The parameters of the feature map. """ return self._feature_map.parameters @property def num_input_parameters(self) -> int: """Returns the number of input parameters in the circuit. Returns: The number of input parameters. """ return len(self._feature_map.parameters) @property def weight_parameters(self) -> ParameterView: """Returns the parameters of the ansatz. These corresponding to the trainable weights. Returns: The parameters of the ansatz. """ return self._ansatz.parameters @property def num_weight_parameters(self) -> int: """Returns the number of weights in the circuit. Returns: The number of weights. """ return len(self._ansatz.parameters)