"""This module creates a wrapper around qiskit-nature mappers."""
from qiskit_nature.second_q.mappers import (
QubitMapper,
JordanWignerMapper,
BravyiKitaevMapper,
)
[docs]
class FermionicToQubitMapper:
[docs]
_mappers = {
'JW': JordanWignerMapper,
'BK': BravyiKitaevMapper,
}
@classmethod
[docs]
def register_mapper(cls, key: str, mapper: QubitMapper):
"""
Register a new mapper class with a given key.
Args:
key (str): The key (name) for the mapper.
mapper (QubitMapper): The mapper class to be registered.
Raises:
ValueError: If the key is already registered.
**Example**
>>> from qiskit_nature.second_q.mappers import TaperedQubitMapper
>>> from qc2.algorithms.utils import FermionicToQubitMapper
>>>
>>> FermionicToQubitMapper.register_mapper('TQM', TaperedQubitMapper)
>>> mapper = FermionicToQubitMapper.from_string('tqm')
"""
if key.upper() in cls._mappers:
raise ValueError(f"Mapper '{key}' is already registered.")
cls._mappers[key.upper()] = mapper
@classmethod
[docs]
def from_string(cls, s):
"""
Retrieve the mapper class corresponding to the provided string.
Args:
s (str): The string identifier of the mapper. Case-insensitive.
Returns:
QubitMapper: The corresponding mapper class.
Raises:
ValueError: If the provided string does not correspond
to any known mapper.
**Example**
>>> from qc2.algorithms.utils import FermionicToQubitMapper
>>> mapper = FermionicToQubitMapper.from_string('jw'))
"""
try:
return cls._mappers[s.upper()]
except KeyError as err:
raise ValueError(f"No mapper found for '{s}'") from err