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IBMBackend

IBMBackend(configuration, service, api_client, instance=None) GitHub(opens in a new tab)

Backend class interfacing with an IBM Quantum backend.

Note
  • You should not instantiate the IBMBackend class directly. Instead, use the methods provided by an QiskitRuntimeService instance to retrieve and handle backends.

This class represents an IBM Quantum backend. Its attributes and methods provide information about the backend. For example, the status() method returns a BackendStatus instance. The instance contains the operational and pending_jobs attributes, which state whether the backend is operational and also the number of jobs in the server queue for the backend, respectively:

status = backend.status()
is_operational = status.operational
jobs_in_queue = status.pending_jobs

Here is list of attributes available on the IBMBackend class:

  • name: backend name.

  • backend_version: backend version in the form X.Y.Z.

  • num_qubits: number of qubits.

  • target: A qiskit.transpiler.Target object for the backend.

  • basis_gates: list of basis gates names on the backend.

  • gates: list of basis gates on the backend.

  • local: backend is local or remote.

  • simulator: backend is a simulator.

  • conditional: backend supports conditional operations.

  • open_pulse: backend supports open pulse.

  • memory: backend supports memory.

  • max_shots: maximum number of shots supported.

  • coupling_map (list): The coupling map for the device

  • supported_instructions (List[str]): Instructions supported by the backend.

  • dynamic_reprate_enabled (bool): whether delay between programs can be set dynamically (ie via rep_delay). Defaults to False.

  • rep_delay_range (List[float]): 2d list defining supported range of repetition delays for backend in μs. First entry is lower end of the range, second entry is higher end of the range. Optional, but will be specified when dynamic_reprate_enabled=True.

  • default_rep_delay (float): Value of rep_delay if not specified by user and dynamic_reprate_enabled=True.

  • n_uchannels: Number of u-channels.

  • u_channel_lo: U-channel relationship on device los.

  • meas_levels: Supported measurement levels.

  • qubit_lo_range: Qubit lo ranges for each qubit with form (min, max) in GHz.

  • meas_lo_range: Measurement lo ranges for each qubit with form (min, max) in GHz.

  • dt: Qubit drive channel timestep in nanoseconds.

  • dtm: Measurement drive channel timestep in nanoseconds.

  • rep_times: Supported repetition times (program execution time) for backend in μs.

  • meas_kernels: Supported measurement kernels.

  • discriminators: Supported discriminators.

  • hamiltonian: An optional dictionary with fields characterizing the system hamiltonian.

  • channel_bandwidth (list): Bandwidth of all channels (qubit, measurement, and U)

  • acquisition_latency (list): Array of dimension n_qubits x n_registers. Latency (in units of dt) to write a measurement result from qubit n into register slot m.

  • conditional_latency (list): Array of dimension n_channels [d->u->m] x n_registers. Latency (in units of dt) to do a conditional operation on channel n from register slot m

  • meas_map (list): Grouping of measurement which are multiplexed

  • max_circuits (int): The maximum number of experiments per job

  • sample_name (str): Sample name for the backend

  • n_registers (int): Number of register slots available for feedback (if conditional is True)

  • register_map (list): An array of dimension n_qubits X n_registers that specifies whether a qubit can store a measurement in a certain register slot.

  • configurable (bool): True if the backend is configurable, if the backend is a simulator

  • credits_required (bool): True if backend requires credits to run a job.

  • online_date (datetime): The date that the device went online

  • display_name (str): Alternate name field for the backend

  • description (str): A description for the backend

  • tags (list): A list of string tags to describe the backend

  • version: version of Backend class (Ex: 1, 2)

  • channels: An optional dictionary containing information of each channel – their purpose, type, and qubits operated on.

  • parametric_pulses (list): A list of pulse shapes which are supported on the backend. For example: ['gaussian', 'constant']

  • processor_type (dict): Processor type for this backend. A dictionary of the form {"family": <str>, "revision": <str>, segment: <str>} such as {"family": "Canary", "revision": "1.0", segment: "A"}.

    • family: Processor family of this backend.
    • revision: Revision version of this processor.
    • segment: Segment this processor belongs to within a larger chip.

IBMBackend constructor.

Parameters

  • configuration (Union[QasmBackendConfiguration, PulseBackendConfiguration]) – Backend configuration.
  • service (QiskitRuntimeService) – Instance of QiskitRuntimeService.
  • api_client (RuntimeClient) – IBM client used to communicate with the server.

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.

Return type

Optional[float]

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.

Return type

dtm

id_warning_issued

= False

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)

Return type

List[Tuple[Instruction, Tuple[int]]]

max_circuits

The maximum number of 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.

Return type

int

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

Return type

meas_map

num_qubits

Return the number of qubits the backend has.

Return type

int

operation_names

A list of instruction names that the backend supports.

Return type

List[str]

operations

A list of Instruction instances that the backend supports.

Return type

List[Instruction]

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

service

Return the service object

Returns

instance of QiskitRuntimeService

Return type

service

session

Return session

Return type

Session

target

A qiskit.transpiler.Target object for the backend.

Return type

Target

Returns

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

__call__

__call__()

Call self as a function.

Return type

IBMBackend

acquire_channel

acquire_channel(qubit) GitHub(opens in a new tab)

Return the acquisition channel for the given qubit.

Returns

The Qubit measurement acquisition line.

Return type

AcquireChannel

cancel_session

cancel_session() GitHub(opens in a new tab)

Cancel session. All pending jobs will be cancelled.

Return type

None

check_faulty

check_faulty(circuit) GitHub(opens in a new tab)

Check if the input circuit uses faulty qubits or edges.

Parameters

circuit (QuantumCircuit) – Circuit to check.

Raises

ValueError – If an instruction operating on a faulty qubit or edge is found.

Return type

None

close_session

close_session() GitHub(opens in a new tab)

Close the session so new jobs will no longer be accepted, but existing queued or running jobs will run to completion. The session will be terminated once there are no more pending jobs.

Return type

None

configuration

configuration() GitHub(opens in a new tab)

Return the backend configuration.

Backend configuration contains fixed information about the backend, such as its name, number of qubits, basis gates, coupling map, quantum volume, etc.

The schema for backend configuration can be found in Qiskit/ibm-quantum-schemas/backend_configuration(opens in a new tab).

Return type

Union[QasmBackendConfiguration, PulseBackendConfiguration]

Returns

The configuration for the backend.

control_channel

control_channel(qubits) GitHub(opens in a new tab)

Return the secondary drive channel for the given qubit

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

Parameters

qubits (Iterable[int]) – Tuple or list of qubits of the form (control_qubit, target_qubit).

Returns

The Qubit measurement acquisition line.

Return type

List[ControlChannel]

defaults

defaults(refresh=False) GitHub(opens in a new tab)

Return the pulse defaults for the backend.

The schema for default pulse configuration can be found in Qiskit/ibm-quantum-schemas/default_pulse_configuration(opens in a new tab).

Parameters

refresh (bool) – If True, re-query the server for the backend pulse defaults. Otherwise, return a cached version.

Return type

Optional[PulseDefaults]

Returns

The backend pulse defaults or None if the backend does not support pulse.

drive_channel

drive_channel(qubit) GitHub(opens in a new tab)

Return the drive channel for the given qubit.

Returns

The Qubit drive channel

Return type

DriveChannel

measure_channel

measure_channel(qubit) GitHub(opens in a new tab)

Return the measure stimulus channel for the given qubit.

Returns

The Qubit measurement stimulus line

Return type

MeasureChannel

open_session

open_session(max_time=None) GitHub(opens in a new tab)

Open session

Return type

Session

properties

properties(refresh=False, datetime=None) GitHub(opens in a new tab)

Return the backend properties, subject to optional filtering.

This data describes qubits properties (such as T1 and T2), gates properties (such as gate length and error), and other general properties of the backend.

The schema for backend properties can be found in Qiskit/ibm-quantum-schemas/backend_properties(opens in a new tab).

Parameters

  • refresh (bool) – If True, re-query the server for the backend properties. Otherwise, return a cached version.
  • datetime (Optional[datetime]) – By specifying datetime, this function returns an instance of the BackendProperties whose timestamp is closest to, but older than, the specified datetime. Note that this is only supported using ibm_quantum runtime.

Return type

Optional[BackendProperties]

Returns

The backend properties or None if the backend properties are not currently available.

Raises

  • TypeError – If an input argument is not of the correct type.
  • NotImplementedError – If datetime is specified when cloud runtime is used.

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 (Union[int, List[int]]) – 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

Return type

Union[QubitProperties, List[QubitProperties]]

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 – if the backend doesn’t support querying the qubit properties

run

run(circuits, dynamic=None, job_tags=None, init_circuit=None, init_num_resets=None, header=None, shots=None, memory=None, meas_level=None, meas_return=None, rep_delay=None, init_qubits=None, use_measure_esp=None, noise_model=None, seed_simulator=None, **run_config) GitHub(opens in a new tab)

Run on the backend. If a keyword specified here is also present in the options attribute/object, the value specified here will be used for this run.

Parameters

  • circuits (Union[QuantumCircuit, str, List[Union[QuantumCircuit, str]]]) – An individual or a list of QuantumCircuit.

  • dynamic (Optional[bool]) – Whether the circuit is dynamic (uses in-circuit conditionals)

  • job_tags (Optional[List[str]]) – Tags to be assigned to the job. The tags can subsequently be used as a filter in the jobs() function call.

  • init_circuit (Optional[QuantumCircuit]) – A quantum circuit to execute for initializing qubits before each circuit. If specified, init_num_resets is ignored. Applicable only if dynamic=True is specified.

  • init_num_resets (Optional[int]) – The number of qubit resets to insert before each circuit execution.

  • or (The following parameters are applicable only if dynamic=False is specified) –

  • to. (defaulted) –

  • header (Optional[Dict]) – User input that will be attached to the job and will be copied to the corresponding result header. Headers do not affect the run. This replaces the old Qobj header.

  • shots (Union[int, float, None]) – Number of repetitions of each circuit, for sampling. Default: 4000 or max_shots from the backend configuration, whichever is smaller.

  • memory (Optional[bool]) – If True, per-shot measurement bitstrings are returned as well (provided the backend supports it). For OpenPulse jobs, only measurement level 2 supports this option.

  • meas_level (Union[int, MeasLevel, None]) –

    Level of the measurement output for pulse experiments. See OpenPulse specification(opens in a new tab) for details:

    • 0, measurements of the raw signal (the measurement output pulse envelope)
    • 1, measurement kernel is selected (a complex number obtained after applying the measurement kernel to the measurement output signal)
    • 2 (default), a discriminator is selected and the qubit state is stored (0 or 1)
  • meas_return (Union[str, MeasReturnType, None]) –

    Level of measurement data for the backend to return. For meas_level 0 and 1:

    • single returns information from every shot.
    • avg returns average measurement output (averaged over number of shots).
  • rep_delay (Optional[float]) – Delay between programs in seconds. Only supported on certain backends (if backend.configuration().dynamic_reprate_enabled=True). If supported, rep_delay must be from the range supplied by the backend (backend.configuration().rep_delay_range). Default is given by backend.configuration().default_rep_delay.

  • init_qubits (Optional[bool]) – Whether to reset the qubits to the ground state for each shot. Default: True.

  • use_measure_esp (Optional[bool]) – Whether to use excited state promoted (ESP) readout for measurements which are the terminal instruction to a qubit. ESP readout can offer higher fidelity than standard measurement sequences. See here(opens in a new tab). Default: True if backend supports ESP readout, else False. Backend support for ESP readout is determined by the flag measure_esp_enabled in backend.configuration().

  • noise_model (Optional[Any]) – Noise model. (Simulators only)

  • seed_simulator (Optional[int]) – Random seed to control sampling. (Simulators only)

  • **run_config – Extra arguments used to configure the run.

Return type

RuntimeJob

Returns

The job to be executed.

Raises

  • IBMBackendApiError – If an unexpected error occurred while submitting the job.

  • IBMBackendApiProtocolError – If an unexpected value received from the server.

  • IBMBackendValueError

    • If an input parameter value is not valid. - If ESP readout is used and the backend does not support this.

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 – If the field passed in is not part of the options

status

status() GitHub(opens in a new tab)

Return the backend status.

Note

If the returned BackendStatus instance has operational=True but status_msg="internal", then the backend is accepting jobs but not processing them.

Return type

BackendStatus

Returns

The status of the backend.

Raises

IBMBackendApiProtocolError – If the status for the backend cannot be formatted properly.

target_history

target_history(datetime=None) GitHub(opens in a new tab)

A qiskit.transpiler.Target object for the backend. :rtype: Target :returns: Target with properties found on datetime

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