qiskit.chemistry.transformations.FermionicTransformation
class FermionicTransformation(transformation=<FermionicTransformationType.FULL: 'full'>, qubit_mapping=<FermionicQubitMappingType.PARITY: 'parity'>, two_qubit_reduction=True, freeze_core=False, orbital_reduction=None, z2symmetry_reduction=None)
A transformation from a fermionic problem, represented by a driver, to a qubit operator.
Parameters
- transformation (
FermionicTransformationType) – full or particle_hole - qubit_mapping (
FermionicQubitMappingType) – ‘jordan_wigner’, ‘parity’ or ‘bravyi_kitaev’ - two_qubit_reduction (
bool) – Whether two qubit reduction should be used, when parity mapping only - freeze_core (
bool) – Whether to freeze core orbitals when possible - orbital_reduction (
Optional[List[int]]) – Orbital list to be frozen or removed - z2symmetry_reduction (
Union[str,List[int],None]) – If z2 symmetry reduction should be applied to resulting qubit operators that are computed. For each symmetry detected the operator will be split in two where each requires one qubit less for computation. So for example 3 symmetries will split in the original operator into 8 new operators each requiring 3 less qubits. Now only one of these operators will have the ground state and be the correct symmetry sector needed for the ground state. Setting ‘auto’ will use an automatic computation of the correct sector. If from other experiments, with the z2symmetry logic, the sector is known, then the tapering values of that sector can be provided (a list of int of values -1, and 1). The default is None meaning no symmetry reduction is done. Note that dipole and other operators such as spin, num particles etc are also symmetry reduced according to the symmetries found in the main operator if this operator commutes with the main operator symmetry. If it does not then the operator will be discarded since no meaningful measurement can take place.
Raises
QiskitChemistryError – Invalid symmetry reduction
__init__
__init__(transformation=<FermionicTransformationType.FULL: 'full'>, qubit_mapping=<FermionicQubitMappingType.PARITY: 'parity'>, two_qubit_reduction=True, freeze_core=False, orbital_reduction=None, z2symmetry_reduction=None)
Parameters
- transformation (
FermionicTransformationType) – full or particle_hole - qubit_mapping (
FermionicQubitMappingType) – ‘jordan_wigner’, ‘parity’ or ‘bravyi_kitaev’ - two_qubit_reduction (
bool) – Whether two qubit reduction should be used, when parity mapping only - freeze_core (
bool) – Whether to freeze core orbitals when possible - orbital_reduction (
Optional[List[int]]) – Orbital list to be frozen or removed - z2symmetry_reduction (
Union[str,List[int],None]) – If z2 symmetry reduction should be applied to resulting qubit operators that are computed. For each symmetry detected the operator will be split in two where each requires one qubit less for computation. So for example 3 symmetries will split in the original operator into 8 new operators each requiring 3 less qubits. Now only one of these operators will have the ground state and be the correct symmetry sector needed for the ground state. Setting ‘auto’ will use an automatic computation of the correct sector. If from other experiments, with the z2symmetry logic, the sector is known, then the tapering values of that sector can be provided (a list of int of values -1, and 1). The default is None meaning no symmetry reduction is done. Note that dipole and other operators such as spin, num particles etc are also symmetry reduced according to the symmetries found in the main operator if this operator commutes with the main operator symmetry. If it does not then the operator will be discarded since no meaningful measurement can take place.
Raises
QiskitChemistryError – Invalid symmetry reduction
Methods
__init__([transformation, qubit_mapping, …]) | type transformationFermionicTransformationType |
build_hopping_operators([excitations]) | Builds the product of raising and lowering operators (basic excitation operators) |
get_default_filter_criterion() | Returns a default filter criterion method to filter the eigenvalues computed by the eigen solver. |
interpret(raw_result) | Interprets an EigenstateResult in the context of this transformation. |
transform(driver[, aux_operators]) | Transformation from the driver to a qubit operator. |
Attributes
commutation_rule | Getter of the commutation rule |
molecule_info | Getter of the molecule information. |
qubit_mapping | Getter of the qubit mapping. |
untapered_qubit_op | Getter for the untapered qubit operator |
build_hopping_operators
build_hopping_operators(excitations='sd')
Builds the product of raising and lowering operators (basic excitation operators)
Parameters
excitations (Union[str, List[List[int]]]) – The excitations to be included in the eom pseudo-eigenvalue problem. If a string (‘s’, ‘d’ or ‘sd’) then all excitations of the given type will be used. Otherwise a list of custom excitations can directly be provided.
Return type
Tuple[Dict[str, WeightedPauliOperator], Dict[str, List[bool]], Dict[str, List[Any]]]
Returns
A tuple containing the hopping operators, the types of commutativities and the excitation indices.
commutation_rule
Getter of the commutation rule
Return type
bool
get_default_filter_criterion
get_default_filter_criterion()
Returns a default filter criterion method to filter the eigenvalues computed by the eigen solver. For more information see also aqua.algorithms.eigen_solvers.NumPyEigensolver.filter_criterion.
In the fermionic case the default filter ensures that the number of particles is being preserved.
Return type
Optional[Callable[[Union[List, ndarray], float, Optional[List[float]]], bool]]
interpret
interpret(raw_result)
Interprets an EigenstateResult in the context of this transformation.
Parameters
raw_result (Union[EigenstateResult, EigensolverResult, MinimumEigensolverResult]) – an eigenstate result object.
Return type
ElectronicStructureResult
Returns
An electronic structure result.
molecule_info
Getter of the molecule information.
Return type
Dict[str, Any]
qubit_mapping
Getter of the qubit mapping.
Return type
str
transform
transform(driver, aux_operators=None)
Transformation from the driver to a qubit operator.
Parameters
- driver (
BaseDriver) – A driver encoding the molecule information. - aux_operators (
Optional[List[FermionicOperator]]) – Additional auxiliaryFermionicOperatorinstances to evaluate.
Return type
Tuple[OperatorBase, List[OperatorBase]]
Returns
A qubit operator and a dictionary of auxiliary operators.
untapered_qubit_op
Getter for the untapered qubit operator