--- title: EstimatorV2 (v0.26) description: API reference for qiskit_ibm_runtime.EstimatorV2 in qiskit-ibm-runtime v0.26 source: https://quantum.cloud.ibm.com/docs/en/api/qiskit-ibm-runtime/0.26/estimator-v2 --- # EstimatorV2 *class* `EstimatorV2(mode=None, backend=None, session=None, options=None)` [GitHub](https://github.com/Qiskit/qiskit-ibm-runtime/tree/stable/0.26/qiskit_ibm_runtime/estimator.py#L53-L231) Class for interacting with Qiskit Runtime Estimator primitive service. Qiskit Runtime Estimator primitive service estimates expectation values of quantum circuits and observables. The [`run()`](#qiskit_ibm_runtime.EstimatorV2.run "qiskit_ibm_runtime.EstimatorV2.run") can be used to submit circuits, observables, and parameters to the Estimator primitive. Following construction, an estimator is used by calling its [`run()`](#qiskit_ibm_runtime.EstimatorV2.run "qiskit_ibm_runtime.EstimatorV2.run") method with a list of PUBs (Primitive Unified Blocs). Each PUB contains four values that, together, define a computation unit of work for the estimator to complete: - a single [`QuantumCircuit`](/docs/api/qiskit/qiskit.circuit.QuantumCircuit), possibly parametrized, whose final state we define as $\psi(\theta)$, - one or more observables (specified as any `ObservablesArrayLike`, including `Pauli`, `SparsePauliOp`, `str`) that specify which expectation values to estimate, denoted $H_j$, and - a collection parameter value sets to bind the circuit against, $\theta_k$. - an optional target precision for expectation value estimates. Here is an example of how the estimator is used. ```python from qiskit.circuit.library import RealAmplitudes from qiskit.quantum_info import SparsePauliOp from qiskit.transpiler.preset_passmanagers import generate_preset_pass_manager from qiskit_ibm_runtime import QiskitRuntimeService, EstimatorV2 as Estimator service = QiskitRuntimeService() backend = service.least_busy(operational=True, simulator=False) psi = RealAmplitudes(num_qubits=2, reps=2) hamiltonian = SparsePauliOp.from_list([("II", 1), ("IZ", 2), ("XI", 3)]) theta = [0, 1, 1, 2, 3, 5] pm = generate_preset_pass_manager(backend=backend, optimization_level=1) isa_psi = pm.run(psi) isa_observables = hamiltonian.apply_layout(isa_psi.layout) estimator = Estimator(backend=backend) # calculate [ ] job = estimator.run([(isa_psi, isa_observables, [theta])]) pub_result = job.result()[0] print(f"Expectation values: {pub_result.data.evs}") ``` Initializes the Estimator primitive. **Parameters** - **mode** (`Union`\[[BackendV1](/docs/api/qiskit/1.4/qiskit.providers.BackendV1), [`BackendV2`](/docs/api/qiskit/qiskit.providers.BackendV2), [`Session`](/docs/api/qiskit-ibm-runtime/0.26/session "qiskit_ibm_runtime.session.Session"), [`Batch`](/docs/api/qiskit-ibm-runtime/0.26/batch "qiskit_ibm_runtime.batch.Batch"), `str`, `None`]) – The execution mode used to make the primitive query. It can be: - A `Backend` if you are using job mode. - A [`Session`](/docs/api/qiskit-ibm-runtime/0.26/session "qiskit_ibm_runtime.Session") if you are using session execution mode. - A [`Batch`](/docs/api/qiskit-ibm-runtime/0.26/batch "qiskit_ibm_runtime.Batch") if you are using batch execution mode. Refer to the [Qiskit Runtime documentation](/docs/run). for more information about the `Execution modes`. - **backend** (`Union`\[`str`, [BackendV1](/docs/api/qiskit/1.4/qiskit.providers.BackendV1), [`BackendV2`](/docs/api/qiskit/qiskit.providers.BackendV2), `None`]) – (DEPRECATED) Backend to run the primitive. This can be a backend name or an [`IBMBackend`](/docs/api/qiskit-ibm-runtime/0.26/ibm-backend "qiskit_ibm_runtime.IBMBackend") instance. If a name is specified, the default account (e.g. `QiskitRuntimeService()`) is used. - **session** (`Optional`\[[`Session`](/docs/api/qiskit-ibm-runtime/0.26/session "qiskit_ibm_runtime.session.Session")]) – (DEPRECATED) Session in which to call the primitive. If both `session` and `backend` are specified, `session` takes precedence. If neither is specified, and the primitive is created inside a [`qiskit_ibm_runtime.Session`](/docs/api/qiskit-ibm-runtime/0.26/session "qiskit_ibm_runtime.Session") context manager, then the session is used. Otherwise if IBM Cloud channel is used, a default backend is selected. - **options** (`Union`\[`Dict`, [`EstimatorOptions`](/docs/api/qiskit-ibm-runtime/0.26/options-estimator-options "qiskit_ibm_runtime.options.estimator_options.EstimatorOptions"), `None`]) – Estimator options, see `EstimatorOptions` for detailed description. **Raises** **NotImplementedError** – If “q-ctrl” channel strategy is used. ## Attributes ### mode Return the execution mode used by this primitive. **Return type** Optional\[[Session](/docs/api/qiskit-ibm-runtime/0.26/session "qiskit_ibm_runtime.Session") | [Batch](/docs/api/qiskit-ibm-runtime/0.26/batch "qiskit_ibm_runtime.Batch")] **Returns** Mode used by this primitive, or `None` if an execution mode is not used. ### options Return options **Return type** `TypeVar`(`OptionsT`, bound= `BaseOptions`) ### session Return session used by this primitive. **Return type** `Optional`\[[`Session`](/docs/api/qiskit-ibm-runtime/0.26/session "qiskit_ibm_runtime.session.Session")] **Returns** Session used by this primitive, or `None` if session is not used. ### version Default value: `2` ## Methods ### run `run(pubs, *, precision=None)` [GitHub](https://github.com/Qiskit/qiskit-ibm-runtime/tree/stable/0.26/qiskit_ibm_runtime/estimator.py#L176-L194) Submit a request to the estimator primitive. **Parameters** - **pubs** (*Iterable\[EstimatorPubLike]*) – An iterable of pub-like (primitive unified bloc) objects, such as tuples `(circuit, observables)` or `(circuit, observables, parameter_values)`. - **precision** (*float | None*) – The target precision for expectation value estimates of each run Estimator Pub that does not specify its own precision. If None the estimator’s default precision value will be used. **Return type** [RuntimeJobV2](/docs/api/qiskit-ibm-runtime/0.26/runtime-job-v2 "qiskit_ibm_runtime.RuntimeJobV2") **Returns** Submitted job.