--- title: BackendV2 (latest version) description: API reference for qiskit.providers.BackendV2 in the latest version of qiskit source: https://eu-de.quantum.cloud.ibm.com/docs/en/api/qiskit/qiskit.providers.BackendV2 --- # BackendV2 *class* `qiskit.providers.BackendV2(provider=None, name=None, description=None, online_date=None, backend_version=None, **fields)` [GitHub](https://github.com/Qiskit/qiskit/tree/stable/2.5/qiskit/providers/backend.py#L38-L330) Bases: [`Backend`](/docs/api/qiskit/qiskit.providers.Backend "qiskit.providers.backend.Backend"), [`ABC`](https://docs.python.org/3/library/abc.html#abc.ABC) Abstract class for Backends This abstract class is to be used for all Backend objects created by a provider. This version differs from earlier abstract Backend classes in that the configuration attribute no longer exists. Instead, attributes exposing equivalent required immutable properties of the backend device are added. For example `backend.configuration().n_qubits` is accessible from `backend.num_qubits` now. The `options` attribute of the backend is used to contain the dynamic user configurable options of the backend. It should be used more for runtime options that configure how the backend is used. For example, something like a `shots` field for a backend that runs experiments which would contain an int for how many shots to execute. A backend object can optionally contain methods named `get_translation_stage_plugin` and `get_scheduling_stage_plugin`. If these methods are present on a backend object and this object is used for [`transpile()`](/docs/api/qiskit/compiler#qiskit.compiler.transpile "qiskit.compiler.transpile") or [`generate_preset_pass_manager()`](/docs/api/qiskit/qiskit.transpiler.generate_preset_pass_manager "qiskit.transpiler.generate_preset_pass_manager") the transpilation process will default to using the output from those methods as the scheduling stage and the translation compilation stage. This enables a backend which has custom requirements for compilation to specify a stage plugin for these stages to enable custom transformation of the circuit to ensure it is runnable on the backend. These hooks are enabled by default and should only be used to enable extra compilation steps if they are **required** to ensure a circuit is executable on the backend or have the expected level of performance. These methods are passed no input arguments and are expected to return a `str` representing the method name which should be a stage plugin (see: [`qiskit.transpiler.preset_passmanagers.plugin`](/docs/api/qiskit/transpiler_plugins#module-qiskit.transpiler.preset_passmanagers.plugin "qiskit.transpiler.preset_passmanagers.plugin") for more details on plugins). The typical expected use case is for a backend provider to implement a stage plugin for `translation` or `scheduling` that contains the custom compilation passes and then for the hook methods on the backend object to return the plugin name so that [`transpile()`](/docs/api/qiskit/compiler#qiskit.compiler.transpile "qiskit.compiler.transpile") will use it by default when targeting the backend. Subclasses of this should override the public method [`run()`](#qiskit.providers.BackendV2.run "qiskit.providers.BackendV2.run") and the internal [`_default_options()`](#qiskit.providers.BackendV2._default_options "qiskit.providers.BackendV2._default_options"): ### \_default\_options *abstractmethod classmethod* `_default_options()` [GitHub](https://github.com/Qiskit/qiskit/tree/stable/2.5/qiskit/providers/backend.py#L181-L194) Return the default options This method will return a [`qiskit.providers.Options`](/docs/api/qiskit/qiskit.providers.Options "qiskit.providers.Options") subclass object that will be used for the default options. These should be the default parameters to use for the options of the backend. **Returns** **A options object with** default values set **Return type** [qiskit.providers.Options](/docs/api/qiskit/qiskit.providers.Options "qiskit.providers.Options") Initialize a BackendV2 based backend **Parameters** - **provider** – An optional backwards reference to the provider object that the backend is from - **name** ([*str*](https://docs.python.org/3/library/stdtypes.html#str) *| None*) – An optional name for the backend - **description** ([*str*](https://docs.python.org/3/library/stdtypes.html#str) *| None*) – An optional description of the backend - **online\_date** ([*datetime*](https://docs.python.org/3/library/datetime.html#datetime.datetime) *| None*) – An optional datetime the backend was brought online - **backend\_version** ([*str*](https://docs.python.org/3/library/stdtypes.html#str) *| None*) – An optional backend version string. This differs from the [`version`](#qiskit.providers.BackendV2.version "qiskit.providers.BackendV2.version") attribute as [`version`](#qiskit.providers.BackendV2.version "qiskit.providers.BackendV2.version") is for the abstract [`Backend`](/docs/api/qiskit/qiskit.providers.Backend "qiskit.providers.Backend") abstract interface version of the object while `backend_version` is for versioning the backend itself. - **fields** – kwargs for the values to use to override the default options. **Raises** [**AttributeError**](https://docs.python.org/3/library/exceptions.html#AttributeError) – If a field is specified that’s outside the backend’s options ## Attributes ### coupling\_map Return the [`CouplingMap`](/docs/api/qiskit/qiskit.transpiler.CouplingMap "qiskit.transpiler.CouplingMap") object ### dt Return the system time resolution of input signals This is required to be implemented if the backend supports Pulse scheduling. **Returns** The input signal timestep in seconds. If the backend doesn’t define `dt`, `None` will be returned. ### dtm Return the system time resolution of output signals **Returns** The output signal timestep in seconds. **Raises** [**NotImplementedError**](https://docs.python.org/3/library/exceptions.html#NotImplementedError) – if the backend doesn’t support querying the output signal timestep ### instruction\_durations Return the [`InstructionDurations`](/docs/api/qiskit/qiskit.transpiler.InstructionDurations "qiskit.transpiler.InstructionDurations") object. ### instructions A list of Instruction tuples on the backend of the form `(instruction, (qubits))` ### max\_circuits The maximum number of circuits that can be run in a single job. If there is no limit this will return None ### meas\_map Return the grouping of measurements which are multiplexed This is required to be implemented if the backend supports Pulse scheduling. **Returns** The grouping of measurements which are multiplexed **Raises** [**NotImplementedError**](https://docs.python.org/3/library/exceptions.html#NotImplementedError) – if the backend doesn’t support querying the measurement mapping ### num\_qubits Return the number of qubits the backend has. ### operation\_names A list of instruction names that the backend supports. ### operations A list of [`Instruction`](/docs/api/qiskit/qiskit.circuit.Instruction "qiskit.circuit.Instruction") instances that the backend supports. ### options Return the options for the backend The options of a backend are the dynamic parameters defining how the backend is used. These are used to control the [`run()`](#qiskit.providers.BackendV2.run "qiskit.providers.BackendV2.run") method. ### provider Return the backend provider. **Returns** the provider responsible for the backend. **Return type** [provider](#qiskit.providers.BackendV2.provider "qiskit.providers.BackendV2.provider") ### target A [`qiskit.transpiler.Target`](/docs/api/qiskit/qiskit.transpiler.Target "qiskit.transpiler.Target") object for the backend. **Return type** [Target](/docs/api/qiskit/qiskit.transpiler.Target "qiskit.transpiler.Target") ### version Default value: `2` ### name Name of the backend. ### description Optional human-readable description. ### online\_date Date that the backend came online. ### backend\_version Version of the backend being provided. This is not the same as [`BackendV2.version`](#qiskit.providers.BackendV2.version "qiskit.providers.BackendV2.version"), which is the version of the [`Backend`](/docs/api/qiskit/qiskit.providers.Backend "qiskit.providers.Backend") abstract interface. ## Methods ### qubit\_properties `qubit_properties(qubit)` [GitHub](https://github.com/Qiskit/qiskit/tree/stable/2.5/qiskit/providers/backend.py#L238-L268) Return QubitProperties for a given qubit. If there are no defined or the backend doesn’t support querying these details this method does not need to be implemented. **Parameters** **qubit** ([*int*](https://docs.python.org/3/library/functions.html#int) *|*[*list*](https://docs.python.org/3/library/stdtypes.html#list)*\[*[*int*](https://docs.python.org/3/library/functions.html#int)*]*) – The qubit to get the [`QubitProperties`](/docs/api/qiskit/qiskit.providers.QubitProperties "qiskit.providers.QubitProperties") object for. This can be a single integer for 1 qubit or a list of qubits and a list of [`QubitProperties`](/docs/api/qiskit/qiskit.providers.QubitProperties "qiskit.providers.QubitProperties") objects will be returned in the same order **Returns** The [`QubitProperties`](/docs/api/qiskit/qiskit.providers.QubitProperties "qiskit.providers.QubitProperties") object for the specified qubit. If a list of qubits is provided a list will be returned. If properties are missing for a qubit this can be `None`. **Raises** [**NotImplementedError**](https://docs.python.org/3/library/exceptions.html#NotImplementedError) – if the backend doesn’t support querying the qubit properties **Return type** [*QubitProperties*](/docs/api/qiskit/qiskit.providers.QubitProperties "qiskit._accelerate.target.QubitProperties") | [list](https://docs.python.org/3/library/stdtypes.html#list)\[[*QubitProperties*](/docs/api/qiskit/qiskit.providers.QubitProperties "qiskit._accelerate.target.QubitProperties")] ### run *abstractmethod* `run(run_input, **options)` [GitHub](https://github.com/Qiskit/qiskit/tree/stable/2.5/qiskit/providers/backend.py#L308-L330) Run on the backend. This method returns a [`Job`](/docs/api/qiskit/qiskit.providers.Job "qiskit.providers.Job") object that runs circuits. Depending on the backend this may be either an async or sync call. It is at the discretion of the provider to decide whether running should block until the execution is finished or not: the Job class can handle either situation. **Parameters** - **run\_input** ([*QuantumCircuit*](/docs/api/qiskit/qiskit.circuit.QuantumCircuit "qiskit.circuit.QuantumCircuit") *or*[*list*](https://docs.python.org/3/library/stdtypes.html#list)) – An individual or a list of [`QuantumCircuit`](/docs/api/qiskit/qiskit.circuit.QuantumCircuit "qiskit.circuit.QuantumCircuit") objects to run on the backend. - **options** – Any kwarg options to pass to the backend for running the config. If a key is also present in the options attribute/object then the expectation is that the value specified will be used instead of what’s set in the options object. **Returns** The job object for the run **Return type** [Job](/docs/api/qiskit/qiskit.providers.Job "qiskit.providers.Job") ### set\_options `set_options(**fields)` [GitHub](https://github.com/Qiskit/qiskit/tree/stable/2.5/qiskit/providers/backend.py#L270-L287) Set the options fields for the backend This method is used to update the options of a backend. If you need to change any of the options prior to running just pass in the kwarg with the new value for the options. **Parameters** **fields** – The fields to update the options **Raises** [**AttributeError**](https://docs.python.org/3/library/exceptions.html#AttributeError) – If the field passed in is not part of the options