Note

This is the documentation for the current state of the development branch of Qiskit Experiments. The documentation or APIs here can change prior to being released.

CorrelatedReadoutError

class CorrelatedReadoutError(physical_qubits=None, backend=None)

Correlated readout error characterization experiment.

Overview

This class constructs the a CorrelatedReadoutMitigator containing the full assignment matrix $A$ characterizing the readout error for the given qubits from the experiment results accessible via the assignment_matrix() method.

Readout errors affect quantum computation during the measurement of the qubits in a quantum device. By characterizing the readout errors, it is possible to construct a readout error mitigator that is used both to obtain a more accurate distribution of the outputs, and more accurate measurements of expectation value for measurables.

The readout mitigator is generated from an assignment matrix: a $2^n\times 2^n$ matrix $A$ such that $A_{y,x}$ is the probability to observe $y$ given the true outcome should be $x$. The assignment matrix is used to compute the mitigation matrix used in the readout error mitigation process itself.

A Correlated readout mitigator uses the full $2^n\times 2^n$ assignment matrix, meaning it can only be used for small values of $n$. The corresponding class in Qiskit is the CorrelatedReadoutMitigator in qiskit.result.

The experiment generates $2^n$ circuits, for every possible $n$-qubit quantum state and constructs the assignment matrix and correlated mitigator from the results.

See CorrelatedReadoutErrorAnalysis documentation for additional information on correlated readout error experiment analysis.

References

[1] Sergey Bravyi, Sarah Sheldon, Abhinav Kandala, David C. Mckay, Jay M. Gambetta, Mitigating measurement errors in multi-qubit experiments, Phys. Rev. A 103, 042605 (2021), doi: 10.1103/PhysRevA.103.042605 (open)

Analysis class reference

CorrelatedReadoutErrorAnalysis

Experiment options

These options can be set by the set_experiment_options() method.

Options

• Defined in the class BaseExperiment:

  • max_circuits (Optional[int])

    Default value: None

    The maximum number of circuits per job when running an experiment on a backend.

Initialization

Initialize a correlated readout error characterization experiment.

Parameters:

• physical_qubits (Optional[Iterable[int]]) – Optional, the backend qubits being characterized for readout error. If None all qubits on the provided backend will be characterized.

• backend (Optional[Backend]) – Optional, the backend to characterize.

Raises:

QiskitError – If args are not valid.

Attributes

CorrelatedReadoutError.analysis	Return the analysis instance for the experiment
CorrelatedReadoutError.backend	Return the backend for the experiment
CorrelatedReadoutError.experiment_options	Return the options for the experiment.
CorrelatedReadoutError.experiment_type	Return experiment type.
CorrelatedReadoutError.num_qubits	Return the number of qubits for the experiment.
CorrelatedReadoutError.physical_qubits	Return the device qubits for the experiment.
CorrelatedReadoutError.run_options	Return options values for the experiment run() method.
CorrelatedReadoutError.transpile_options	Return the transpiler options for the run() method.

Methods

CorrelatedReadoutError.circuits()	Returns the experiment's circuits
CorrelatedReadoutError.config()	Return the config dataclass for this experiment
CorrelatedReadoutError.copy()	Return a copy of the experiment
CorrelatedReadoutError.from_config(config)	Initialize an experiment from experiment config
CorrelatedReadoutError.run([backend, ...])	Run an experiment and perform analysis.
CorrelatedReadoutError.set_experiment_options(...)	Set the experiment options.
CorrelatedReadoutError.set_run_options(**fields)	Set options values for the experiment run() method.
CorrelatedReadoutError.set_transpile_options(...)	Set the transpiler options for run() method.