137 lines
4.1 KiB
Plaintext
137 lines
4.1 KiB
Plaintext
---
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title: Estimator
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description: API reference for qiskit.primitives.Estimator
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in_page_toc_min_heading_level: 1
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python_api_type: class
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python_api_name: qiskit.primitives.Estimator
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---
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# Estimator
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<Class id="qiskit.primitives.Estimator" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.23/qiskit/primitives/estimator.py" signature="Estimator(circuits: Iterable[QuantumCircuit] | QuantumCircuit | None = None, observables: Iterable[SparsePauliOp] | SparsePauliOp | None = None, parameters: Iterable[Iterable[Parameter]] | None = None, **kwargs)" modifiers="class">
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Bases: [`qiskit.primitives.base.base_estimator.BaseEstimator`](qiskit.primitives.BaseEstimator "qiskit.primitives.base.base_estimator.BaseEstimator")
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Reference implementation of [`BaseEstimator`](qiskit.primitives.BaseEstimator "qiskit.primitives.BaseEstimator").
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**Run Options**
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* **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.
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* **seed** (np.random.Generator or int) – Set a fixed seed or generator for the normal distribution. If shots is None, this option is ignored.
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**Parameters**
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* **circuits** – circuits that represent quantum states.
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* **observables** – observables to be estimated.
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* **parameters** – Parameters of each of the quantum circuits. Defaults to `[circ.parameters for circ in circuits]`.
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* **options** – Default options.
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**Raises**
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**QiskitError** – if some classical bits are not used for measurements.
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## Methods
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### close
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<Function id="qiskit.primitives.Estimator.close" signature="Estimator.close()">
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Close the session and free resources
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</Function>
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### run
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<Function id="qiskit.primitives.Estimator.run" signature="Estimator.run(circuits, observables, parameter_values=None, **run_options)">
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Run the job of the estimation of expectation value(s).
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`circuits`, `observables`, and `parameter_values` should have the same length. The i-th element of the result is the expectation of observable
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```python
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obs = observables[i]
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```
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for the state prepared by
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```python
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circ = circuits[i]
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```
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with bound parameters
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```python
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values = parameter_values[i].
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```
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**Parameters**
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* **circuits** – one or more circuit objects.
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* **observables** – one or more observable objects. Several formats are allowed; importantly, `str` should follow the string representation format for [`Pauli`](qiskit.quantum_info.Pauli "qiskit.quantum_info.Pauli") objects.
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* **parameter\_values** – concrete parameters to be bound.
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* **run\_options** – runtime options used for circuit execution.
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**Returns**
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The job object of EstimatorResult.
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**Raises**
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* **TypeError** – Invalid argument type given.
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* **ValueError** – Invalid argument values given.
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</Function>
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### set\_options
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<Function id="qiskit.primitives.Estimator.set_options" signature="Estimator.set_options(**fields)">
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Set options values for the estimator.
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**Parameters**
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**\*\*fields** – The fields to update the options
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</Function>
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## Attributes
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### circuits
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<Attribute id="qiskit.primitives.Estimator.circuits">
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Quantum circuits that represents quantum states.
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**Returns**
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The quantum circuits.
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</Attribute>
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### observables
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<Attribute id="qiskit.primitives.Estimator.observables">
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Observables to be estimated.
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**Returns**
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The observables.
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</Attribute>
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### options
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<Attribute id="qiskit.primitives.Estimator.options">
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Return options values for the estimator.
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**Return type**
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[`Options`](qiskit.providers.Options "qiskit.providers.options.Options")
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**Returns**
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options
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</Attribute>
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### parameters
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<Attribute id="qiskit.primitives.Estimator.parameters">
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Parameters of the quantum circuits.
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**Returns**
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Parameters, where `parameters[i][j]` is the j-th parameter of the i-th circuit.
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</Attribute>
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</Class>
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