BaseEstimatorV1
qiskit.primitives.BaseEstimatorV1(*, options=None)
Bases: BasePrimitive, Generic(opens in a new tab)[T]
Estimator V1 base class.
Base class for Estimator that estimates expectation values of quantum circuits and observables.
An estimator is initialized with an empty parameter set. The estimator is used to create a JobV1, via the qiskit.primitives.Estimator.run() method. This method is called with the following parameters
- quantum circuits (): list of (parameterized) quantum circuits (a list of
QuantumCircuitobjects). - observables (): a list of
SparsePauliOpobjects. - parameter values (): list of sets of values to be bound to the parameters of the quantum circuits (list of list of float).
The method returns a JobV1 object, calling qiskit.providers.JobV1.result() yields the a list of expectation values plus optional metadata like confidence intervals for the estimation.
Here is an example of how the estimator is used.
from qiskit.primitives import Estimator
from qiskit.circuit.library import RealAmplitudes
from qiskit.quantum_info import SparsePauliOp
psi1 = RealAmplitudes(num_qubits=2, reps=2)
psi2 = RealAmplitudes(num_qubits=2, reps=3)
H1 = SparsePauliOp.from_list([("II", 1), ("IZ", 2), ("XI", 3)])
H2 = SparsePauliOp.from_list([("IZ", 1)])
H3 = SparsePauliOp.from_list([("ZI", 1), ("ZZ", 1)])
theta1 = [0, 1, 1, 2, 3, 5]
theta2 = [0, 1, 1, 2, 3, 5, 8, 13]
theta3 = [1, 2, 3, 4, 5, 6]
estimator = Estimator()
# calculate [ <psi1(theta1)|H1|psi1(theta1)> ]
job = estimator.run([psi1], [H1], [theta1])
job_result = job.result() # It will block until the job finishes.
print(f"The primitive-job finished with result {job_result}"))
# calculate [ <psi1(theta1)|H1|psi1(theta1)>,
# <psi2(theta2)|H2|psi2(theta2)>,
# <psi1(theta3)|H3|psi1(theta3)> ]
job2 = estimator.run([psi1, psi2, psi1], [H1, H2, H3], [theta1, theta2, theta3])
job_result = job2.result()
print(f"The primitive-job finished with result {job_result}")Creating an instance of an Estimator, or using one in a with context opens a session that holds resources until the instance is close() ed or the context is exited.
Parameters
options (dict(opens in a new tab) | None) – Default options.
Attributes
options
Return options values for the estimator.
Returns
options
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 | str(opens in a new tab)] | BaseOperator | str(opens in a new tab)) – one or more observable objects. Several formats are allowed; importantly,
strshould follow the string representation format forPauliobjects. - parameter_values (Sequence[Sequence[float(opens in a new tab)]] | Sequence[float(opens in a new tab)] | float(opens in a new tab) | None) – concrete parameters to be bound.
- run_options – runtime options used for circuit execution.
Returns
The job object of EstimatorResult.
Raises
- TypeError(opens in a new tab) – Invalid argument type given.
- ValueError(opens in a new tab) – 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