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BackendV2

qiskit.providers.BackendV2(provider=None, name=None, description=None, online_date=None, backend_version=None, **fields)GitHub(opens in a new tab)

Bases: Backend, ABC(opens in a new tab)

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.

If migrating a provider from BackendV1 one thing to keep in mind is for backwards compatibility you might need to add a configuration method that will build a BackendConfiguration object and BackendProperties from the attributes defined in this class for backwards compatibility.

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() or 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 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() will use it by default when targetting the backend.

Subclasses of this should override the public method run() and the internal _default_options():

_default_options

abstract classmethod _default_options()

Return the default options

This method will return a 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

Initialize a BackendV2 based backend

Parameters

  • provider (Provider) – An optional backwards reference to the Provider object that the backend is from
  • name (str(opens in a new tab)) – An optional name for the backend
  • description (str(opens in a new tab)) – An optional description of the backend
  • online_date (datetime(opens in a new tab)) – An optional datetime the backend was brought online
  • backend_version (str(opens in a new tab)) – An optional backend version string. This differs from the version attribute as version is for the abstract 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(opens in a new tab) – If a field is specified that’s outside the backend’s options


Attributes

coupling_map

Return the 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(opens in a new tab) – if the backend doesn’t support querying the output signal timestep

instruction_durations

Return the InstructionDurations object.

instruction_schedule_map

Return the InstructionScheduleMap for the instructions defined in this backend’s target.

instructions

A list of Instruction tuples on the backend of the form (instruction, (qubits)

max_circuits

The maximum number of circuits (or Pulse schedules) 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(opens in a new tab) – 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 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() method.

provider

Return the backend Provider.

Returns

the Provider responsible for the backend.

Return type

Provider

target

A qiskit.transpiler.Target object for the backend.

Return type

Target

version

= 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, which is the version of the Backend abstract interface.


Methods

acquire_channel

acquire_channel(qubit)

Return the acquisition channel for the given qubit.

This is required to be implemented if the backend supports Pulse scheduling.

Returns

The Qubit measurement acquisition line.

Return type

AcquireChannel

Raises

NotImplementedError(opens in a new tab) – if the backend doesn’t support querying the measurement mapping

control_channel

control_channel(qubits)

Return the secondary drive channel for the given qubit

This is typically utilized for controlling multiqubit interactions. This channel is derived from other channels.

This is required to be implemented if the backend supports Pulse scheduling.

Parameters

qubits (Iterable(opens in a new tab)[int(opens in a new tab)]) – Tuple or list of qubits of the form (control_qubit, target_qubit).

Returns

The multi qubit control line.

Return type

List[ControlChannel]

Raises

NotImplementedError(opens in a new tab) – if the backend doesn’t support querying the measurement mapping

drive_channel

drive_channel(qubit)

Return the drive channel for the given qubit.

This is required to be implemented if the backend supports Pulse scheduling.

Returns

The Qubit drive channel

Return type

DriveChannel

Raises

NotImplementedError(opens in a new tab) – if the backend doesn’t support querying the measurement mapping

measure_channel

measure_channel(qubit)

Return the measure stimulus channel for the given qubit.

This is required to be implemented if the backend supports Pulse scheduling.

Returns

The Qubit measurement stimulus line

Return type

MeasureChannel

Raises

NotImplementedError(opens in a new tab) – if the backend doesn’t support querying the measurement mapping

qubit_properties

qubit_properties(qubit)

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(opens in a new tab) |List(opens in a new tab)[int(opens in a new tab)]) – The qubit to get the QubitProperties object for. This can be a single integer for 1 qubit or a list of qubits and a list of QubitProperties objects will be returned in the same order

Returns

The 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(opens in a new tab) – if the backend doesn’t support querying the qubit properties

Return type

QubitProperties | List(opens in a new tab)[QubitProperties]

run

abstract run(run_input, **options)

Run on the backend.

This method returns a 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

Returns

The job object for the run

Return type

Job

set_options

set_options(**fields)

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(opens in a new tab) – If the field passed in is not part of the options

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