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BackendV1

qiskit.providers.BackendV1(configuration, provider=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. There are several classes of information contained in a Backend. The first are the attributes of the class itself. These should be used to defined the immutable characteristics of the backend. 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. The properties attribute is optionally defined BackendProperties object and is used to return measured properties, or properties of a backend that may change over time. The simplest example of this would be a version string, which will change as a backend is updated, but also could be something like noise parameters for backends that run experiments.

This first version of the Backend abstract class is written to be mostly backwards compatible with the legacy providers interface. This includes reusing the model objects BackendProperties and BackendConfiguration. This was done to ease the transition for users and provider maintainers to the new versioned providers. Expect, future versions of this abstract class to change the data model and interface.

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 backend class

Parameters

  • configuration (BackendConfiguration) – A backend configuration object for the backend object.
  • provider (qiskit.providers.Provider) – Optionally, the provider object that this Backend comes from.
  • fields – kwargs for the values to use to override the default options.

Raises

AttributeError(opens in a new tab) – if input field not a valid options

In addition to the public abstract methods, subclasses should also implement the following private methods:

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


Attributes

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.

version

= 1


Methods

configuration

configuration()

Return the backend configuration.

Returns

the configuration for the backend.

Return type

BackendConfiguration

name

name()

Return the backend name.

Returns

the name of the backend.

Return type

str(opens in a new tab)

properties

properties()

Return the backend properties.

Returns

the configuration for the backend. If the backend does not support properties, it returns None.

Return type

BackendProperties

provider

provider()

Return the backend Provider.

Returns

the Provider responsible for the backend.

Return type

Provider

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

  • run_input (QuantumCircuit orSchedule orlist(opens in a new tab)) – An individual or a list of QuantumCircuit or Schedule objects to run on the backend. For legacy providers migrating to the new versioned providers, provider interface a QasmQobj or PulseQobj objects should probably be supported too (but deprecated) for backwards compatibility. Be sure to update the docstrings of subclasses implementing this method to document that. New provider implementations should not do this though as qiskit.qobj will be deprecated and removed along with the legacy providers interface.
  • 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

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

status

status()

Return the backend status.

Returns

the status of the backend.

Return type

BackendStatus

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