Source code for qiskit.algorithms.eigen_solvers.eigen_solver

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# (C) Copyright IBM 2020, 2022.
# This code is licensed under the Apache License, Version 2.0. You may
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"""The Eigensolver interface"""
from __future__ import annotations
from abc import ABC, abstractmethod

import numpy as np

from qiskit.opflow import OperatorBase
from qiskit.utils.deprecation import deprecate_func
from ..algorithm_result import AlgorithmResult
from ..list_or_dict import ListOrDict

[docs]class Eigensolver(ABC): """Deprecated: Eigensolver Interface. The Eigensolver interface has been superseded by the :class:`qiskit.algorithms.eigensolvers.Eigensolver` interface. This interface will be deprecated in a future release and subsequently removed after that. Algorithms that can compute eigenvalues for an operator may implement this interface to allow different algorithms to be used interchangeably. """ @deprecate_func( additional_msg=( "Instead, use the interface ``qiskit.algorithms.eigensolvers.Eigensolver``. See " " for a migration guide." ), since="0.24.0", ) def __init__(self) -> None: pass
[docs] @abstractmethod def compute_eigenvalues( self, operator: OperatorBase, aux_operators: ListOrDict[OperatorBase] | None = None ) -> "EigensolverResult": """ Computes eigenvalues. Operator and aux_operators can be supplied here and if not None will override any already set into algorithm so it can be reused with different operators. While an operator is required by algorithms, aux_operators are optional. To 'remove' a previous aux_operators array use an empty list here. Args: operator: Qubit operator of the Observable aux_operators: Optional list of auxiliary operators to be evaluated with the eigenstate of the minimum eigenvalue main result and their expectation values returned. For instance in chemistry these can be dipole operators, total particle count operators so we can get values for these at the ground state. Returns: EigensolverResult """ return EigensolverResult()
[docs] @classmethod def supports_aux_operators(cls) -> bool: """Whether computing the expectation value of auxiliary operators is supported. Returns: True if aux_operator expectations can be evaluated, False otherwise """ return False
[docs]class EigensolverResult(AlgorithmResult): """Deprecated: Eigensolver Result. The EigensolverResult class has been superseded by the :class:`qiskit.algorithms.eigensolvers.EigensolverResult` class. This class will be deprecated in a future release and subsequently removed after that. """ @deprecate_func( additional_msg=( "Instead, use the class ``qiskit.algorithms.eigensolvers.EigensolverResult``. " "See for a migration guide." ), since="0.24.0", ) def __init__(self) -> None: super().__init__() self._eigenvalues: np.ndarray | None = None self._eigenstates: np.ndarray | None = None self._aux_operator_eigenvalues: list[ListOrDict[tuple[complex, complex]]] | None = None @property def eigenvalues(self) -> np.ndarray | None: """returns eigen values""" return self._eigenvalues @eigenvalues.setter def eigenvalues(self, value: np.ndarray) -> None: """set eigen values""" self._eigenvalues = value @property def eigenstates(self) -> np.ndarray | None: """return eigen states""" return self._eigenstates @eigenstates.setter def eigenstates(self, value: np.ndarray) -> None: """set eigen states""" self._eigenstates = value @property def aux_operator_eigenvalues(self) -> list[ListOrDict[tuple[complex, complex]]] | None: """Return aux operator expectation values. These values are in fact tuples formatted as (mean, standard deviation). """ return self._aux_operator_eigenvalues @aux_operator_eigenvalues.setter def aux_operator_eigenvalues(self, value: list[ListOrDict[tuple[complex, complex]]]) -> None: """set aux operator eigen values""" self._aux_operator_eigenvalues = value