---
title: Estimator (latest version)
description: API reference for qiskit_ibm_runtime.executor_estimator.Estimator in the latest version of qiskit-ibm-runtime
source: https://quantum.cloud.ibm.com/docs/en/api/qiskit-ibm-runtime/executor-estimator-estimator
---

# Estimator

*class* `Estimator(mode=None, options=None)`

[GitHub](https://github.com/Qiskit/qiskit-ibm-runtime/tree/stable/0.50/qiskit_ibm_runtime/executor_estimator/estimator.py#L46-L273)

Bases: [`BaseEstimatorV2`](/docs/api/qiskit/qiskit.primitives.BaseEstimatorV2)

Client-side Estimator primitive for IBM Quantum Compute (formerly Qiskit Runtime).

This is an implementation of Estimator built on top of the Executor primitive, enabling transparent client-side processing with faster feedback loops and greater user control.

**Example**

```python
from qiskit import QuantumCircuit
from qiskit.quantum_info import SparsePauliOp
from qiskit_ibm_runtime import QiskitRuntimeService
from qiskit_ibm_runtime.executor_estimator import Estimator

service = QiskitRuntimeService()
backend = service.least_busy(operational=True, simulator=False)

# Create a simple circuit
circuit = QuantumCircuit(2)
circuit.h(0)
circuit.cx(0, 1)

# Define observable
observable = SparsePauliOp.from_list([("ZZ", 1), ("XX", 1)])

# Run the estimator with options
estimator = Estimator(mode=backend)
estimator.options.default_precision = 0.01
estimator.options.execution.init_qubits = True
job = estimator.run([(circuit, observable)])
result = job.result()
```

**Parameters**

- **mode** (*BackendV2 |* [*Session*](/docs/api/qiskit-ibm-runtime/session "qiskit_ibm_runtime.Session")  *|*[*Batch*](/docs/api/qiskit-ibm-runtime/batch "qiskit_ibm_runtime.Batch") *| None*) –

  The execution mode used to make the primitive query. It can be:

  - A [`BackendV2`](/docs/api/qiskit/qiskit.providers.BackendV2) if you are using job mode.
  - A [`Session`](/docs/api/qiskit-ibm-runtime/session "qiskit_ibm_runtime.Session") if you are using session execution mode.
  - A [`Batch`](/docs/api/qiskit-ibm-runtime/batch "qiskit_ibm_runtime.Batch") if you are using batch execution mode.

  Refer to the [IBM Quantum Compute documentation](/docs/guides/execution-modes) for more information about execution modes.

- **options** ([*EstimatorOptions*](/docs/api/qiskit-ibm-runtime/options-models-estimator-options "qiskit_ibm_runtime.options_models.estimator.EstimatorOptions")) – Estimator options. See [`EstimatorOptions`](/docs/api/qiskit-ibm-runtime/options-models-estimator-options "qiskit_ibm_runtime.options_models.EstimatorOptions") for all available options.

## Attributes

### mode

Return the execution mode used by this primitive.

**Returns**

Mode used by this primitive, or `None` if an execution mode is not used.

### options

Type: [`EstimatorOptions`](/docs/api/qiskit-ibm-runtime/options-models-estimator-options "qiskit_ibm_runtime.options_models.estimator.EstimatorOptions")

The options of this Estimator.

## Methods

### backend

`backend()`

[GitHub](https://github.com/Qiskit/qiskit-ibm-runtime/tree/stable/0.50/qiskit_ibm_runtime/executor_estimator/estimator.py#L126-L128)

Return the backend the primitive query will be run on.

**Return type**

BackendV2

### finalize\_options

`finalize_options()`

[GitHub](https://github.com/Qiskit/qiskit-ibm-runtime/tree/stable/0.50/qiskit_ibm_runtime/executor_estimator/estimator.py#L188-L211)

Construct and finalize the Estimator options.

This method combines the configured resilience level with the user-provided option to produce the final [`EstimatorOptions`](/docs/api/qiskit-ibm-runtime/options-models-estimator-options "qiskit_ibm_runtime.options_models.EstimatorOptions") instance used inside a call to [`run()`](#qiskit_ibm_runtime.executor_estimator.Estimator.run "qiskit_ibm_runtime.executor_estimator.Estimator.run").

The process used to produce the finalized options is as follows:

1. Initialize a new [`EstimatorOptions`](/docs/api/qiskit-ibm-runtime/options-models-estimator-options "qiskit_ibm_runtime.options_models.EstimatorOptions") object with defaults determined by [`resilience_level`](/docs/api/qiskit-ibm-runtime/options-models-estimator-options#resilience_level "qiskit_ibm_runtime.options_models.EstimatorOptions.resilience_level").

2. Apply user-specified options, skipping the fields left as `None` that are intended to inherit the resilience-level defaults.

3. Enforce required option dependencies. Specifically:

   - Enabling measurement mitigation automatically enables measurement twirling.
   - Enabling gate-based mitigation techniques (such as PEA-based ZNE or PEC) automatically enables both gate and measurement twirling.

**Returns**

The finalized [`EstimatorOptions`](/docs/api/qiskit-ibm-runtime/options-models-estimator-options "qiskit_ibm_runtime.options_models.EstimatorOptions") object.

**Return type**

[*EstimatorOptions*](/docs/api/qiskit-ibm-runtime/options-models-estimator-options "qiskit_ibm_runtime.options_models.estimator.EstimatorOptions")

### find\_unique\_layers

`find_unique_layers(pubs, types='gates')`

[GitHub](https://github.com/Qiskit/qiskit-ibm-runtime/tree/stable/0.50/qiskit_ibm_runtime/executor_estimator/estimator.py#L139-L186)

Return the unique boxed layers found across the given PUBs.

The `types` of layers can be either `"gates"` or `"all"`, corresponding to only gate layers or all layers, respectively. The returned list then contains one instance of each distinct boxed layer (represented as a `CircuitInstruction`) appearing in the input PUBs.

For example, for noise learning, keep only the qubit gate layers:

```python
est = Estimator(mode, options)
est.options.resilience.pec_mitigation = True

layers = est.find_unique_layers(pubs, types="gates")

results = NoiseLearnerV3(mode).run(layers).result()
pauli_linblad_maps = results.to_pauli_lindblad_maps()

# Assign the learned model so PEC uses it on the next run.
est.options.resilience.layer_noise_model = zip(layers, pauli_linblad_maps)
```

**Parameters**

- **pubs** (*Iterable\[EstimatorPubLike]*) – The list of PUBs to return a list of unique boxes for.
- **types** (*Literal\['gates', 'all']*) – The types of layers to return. Can be either `"gates"` or `"all"`.

**Returns**

The unique boxed layers of a certain type found across the given PUBs.

**Return type**

list\[CircuitInstruction]

### run

`run(pubs, *, precision=None, dry_run=False)`

[GitHub](https://github.com/Qiskit/qiskit-ibm-runtime/tree/stable/0.50/qiskit_ibm_runtime/executor_estimator/estimator.py#L213-L273)

Submit a request to the estimator primitive.

For moderate and complex workloads, the client-side processing done to map estimator inputs to executor inputs can be resource intensive and cause a delay between invoking the function and the `job` being submitted. In order to check the progress of the call, it is recommended to setup logging (with an `INFO` level) - see [IBM Quantum Compute documentation](/docs/api/qiskit-ibm-runtime/runtime-service#logging) for more information.

**Parameters**

- **pubs** (*Iterable\[EstimatorPubLike]*) – An iterable of pub-like objects. For example, a list of circuits and observables or tuples `(circuit, observables, parameter_values)`.
- **precision** (*float | None*) – The target precision for expectation value estimates of each estimator pub that does not specify its own precision. If `None`, the value from `options.default_precision` will be used.
- **dry\_run** (*bool*) – If `True`, performs a dry run without executing the job on a QPU. This mode can be used to validate the job, estimate usage consumption, and retrieve circuit timing metadata. Returned results preserve the expected schema but contain **randomized mock data** rather than actual or simulated measurement results. Unlike the fake backends, the processing of this dry run happens on the server-side, so the job may not finish immediately and access to this feature may be restricted.

**Returns**

The submitted job.

**Raises**

- **ValueError** – If backend is not provided.
- **IBMInputValueError** – If no pubs are provided, if precision is not properly specified, or if unsupported options are detected.

**Return type**

[RuntimeJobV2](/docs/api/qiskit-ibm-runtime/runtime-job-v2 "qiskit_ibm_runtime.RuntimeJobV2") | LocalRuntimeJob