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Estimator

class qiskit.primitives.Estimator(*, options=None)

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Bases: BaseEstimator[PrimitiveJob[EstimatorResult]]

Reference implementation of BaseEstimator.

Run Options

  • shots (None or int) – The number of shots. If None, it calculates the exact expectation values. Otherwise, it samples from normal distributions with standard errors as standard deviations using normal distribution approximation.
  • seed (np.random.Generator or int) – Set a fixed seed or generator for the normal distribution. If shots is None, this option is ignored.

Parameters

options (dict | None) – Default options.

Raises

QiskitError – if some classical bits are not used for measurements.


Attributes

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.


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, str should follow the string representation format for Pauli objects.
  • 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

Return type

T

set_options

set_options(**fields)

Set options values for the estimator.

Parameters

**fields – The fields to update the options

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