BackendEstimator
class qiskit.primitives.BackendEstimator(backend, options=None, abelian_grouping=True, bound_pass_manager=None, skip_transpilation=False)
Bases: BaseEstimator[PrimitiveJob[EstimatorResult]]
Evaluates expectation value using Pauli rotation gates.
The BackendEstimator class is a generic implementation of the BaseEstimator interface that is used to wrap a BackendV2 (or BackendV1) object in the BaseEstimator API. It facilitates using backends that do not provide a native BaseEstimator implementation in places that work with BaseEstimator, such as algorithms in qiskit.algorithms including VQE. However, if you’re using a provider that has a native implementation of BaseEstimator, it is a better choice to leverage that native implementation as it will likely include additional optimizations and be a more efficient implementation. The generic nature of this class precludes doing any provider- or backend-specific optimizations.
Initialize a new BackendEstimator instance
Parameters
- backend (BackendV1 |BackendV2) – Required: the backend to run the primitive on
- options (dict | None) – Default options.
- abelian_grouping (bool) – Whether the observable should be grouped into commuting
- bound_pass_manager (PassManager | None) – An optional pass manager to run after parameter binding.
- skip_transpilation (bool) – If this is set to True the internal compilation of the input circuits is skipped and the circuit objects will be directly executed when this object is called.
Attributes
backend
Returns: The backend which this estimator object based on
circuits
Quantum circuits that represents quantum states.
Returns
The quantum circuits.
observables
Observables to be estimated.
Returns
The observables.
options
Return options values for the estimator.
Returns
options
parameters
Parameters of the quantum circuits.
Returns
Parameters, where parameters[i][j] is the j-th parameter of the i-th circuit.
preprocessed_circuits
Transpiled quantum circuits produced by preprocessing :returns: List of the transpiled quantum circuit
transpile_options
Return the transpiler options for transpiling the circuits.
transpiled_circuits
Transpiled quantum circuits. :returns: List of the transpiled quantum circuit
Raises
QiskitError – if the instance has been closed.
Methods
run
run(circuits, observables, parameter_values=None, **run_options)
Run the job of the estimation of expectation value(s).
circuits, observables, and parameter_values should have the same length. The i-th element of the result is the expectation of observable
obs = observables[i]for the state prepared by
circ = circuits[i]with bound parameters
values = parameter_values[i].Parameters
- circuits (Sequence[QuantumCircuit] | QuantumCircuit) – one or more circuit objects.
- observables (Sequence[BaseOperator | PauliSumOp |str] | BaseOperator | PauliSumOp |str) – one or more observable objects. Several formats are allowed; importantly,
strshould follow the string representation format forPauliobjects. - parameter_values (Sequence[Sequence[float]] | Sequence[float] | float | None) – concrete parameters to be bound.
- run_options – runtime options used for circuit execution.
Returns
The job object of EstimatorResult.
Raises
- TypeError – Invalid argument type given.
- ValueError – Invalid argument values given.
Return type
T
set_options
set_options(**fields)
Set options values for the estimator.
Parameters
**fields – The fields to update the options
set_transpile_options
set_transpile_options(**fields)
Set the transpiler options for transpiler. :param **fields: The fields to update the options