Código fuente para qiskit_nature.second_q.hamiltonians.vibrational_energy

# This code is part of a Qiskit project.
# (C) Copyright IBM 2021, 2023.
# 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
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"""The vibrational energy Hamiltonian."""

from __future__ import annotations

import qiskit_nature  # pylint: disable=unused-import
from qiskit_nature.second_q.operators import VibrationalIntegrals, VibrationalOp

from .hamiltonian import Hamiltonian

[documentos]class VibrationalEnergy(Hamiltonian): r"""The vibrational energy Hamiltonian. This class implements the following Hamiltonian: .. math:: \sum_{l=1}^L \sum_{k_l,h_l}^{N_l} \langle \phi_{k_l} | T(Q_l) + V^{[l]}(Q_l) | \phi_{h_l} \rangle a^\dagger_{k_l} a_{h_l} + \sum_{l<m}^L \sum_{k_l,h_l}^{N_l} \sum_{k_m,h_m}^{N_m} \langle \phi_{k_l} \phi_{k_m} | V^{[l,m]}(Q_l, Q_m) | \phi_{h_l} \phi_{h_m} \rangle a^\dagger_{k_l} a^\dagger_{k_m} a_{h_l} a_{h_m} + \ldots where :math:`Q` denotes a vibrational mode, :math:`T` denotes the kinetic term, and :math:`V` denotes the potential terms acting on multiple modes. The subscripts :math:`k` and :math:`h` are indexing the modals which each mode :math:`l` gets expanded into. For a detailed explanation please refer to reference [1]. The following attributes can be set via the initializer but can also be read and updated once the ``VibrationalEnergy`` object has been constructed. Attributes: vibrational_integrals (VibrationalIntegrals): the integral coefficients. truncation_order (int | None): the maximum order of multi-body terms to include in the operator. References: [1]: P. Ollitrault et al. `arXiv:2003.12578 <https://arxiv.org/abs/2003.12578>`_. """ def __init__( self, vibrational_integrals: VibrationalIntegrals, *, truncation_order: int | None = None, ) -> None: """ Args: vibrational_integrals: the container with the integral coefficients. truncation_order: the maximum order of multi-body terms to include in the operator. """ self.vibrational_integrals = vibrational_integrals self.truncation_order = truncation_order @property def register_length(self) -> int | None: return None
[documentos] @classmethod def from_raw_integrals(cls, integrals: dict[tuple[int, ...], complex]) -> VibrationalEnergy: """Constructs a hamiltonian instance from raw integrals. This function simply calls :meth:`qiskit_nature.second_q.operators.VibrationalIntegrals.from_raw_integrals`. See its documentation for more details. Args: integrals: a mapping of matrix index tuples to coefficients. Returns: The resulting ``VibrationalEnergy`` instance. """ return cls(VibrationalIntegrals.from_raw_integrals(integrals))
[documentos] def second_q_op(self) -> VibrationalOp: """Returns the second quantized vibrational energy operator. Returns: A ``dict`` of ``VibrationalOp`` objects. """ truncated_integrals = self.vibrational_integrals if self.truncation_order is not None: truncated_integrals = VibrationalIntegrals( { key: value for key, value in self.vibrational_integrals.items() if len(key) <= 3 * self.truncation_order }, validate=False, ) return VibrationalOp.from_polynomial_tensor(truncated_integrals)
[documentos] def interpret( self, result: "qiskit_nature.second_q.problems.EigenstateResult" # type: ignore[name-defined] ) -> None: """Interprets an :class:`~qiskit_nature.second_q.problems.EigenstateResult`. Args: result: The result to add meaning to. """