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.

ProcessTomography

class ProcessTomography(circuit, backend=None, physical_qubits=None, measurement_basis=<PauliMeasurementBasis: PauliMeasurementBasis>, measurement_indices=None, preparation_basis=<PauliPreparationBasis: PauliPreparationBasis>, preparation_indices=None, basis_indices=None, conditional_circuit_clbits=False, analysis='default', target='default')

An experiment to reconstruct the quantum channel from measurement data.

Overview

Quantum process tomography (QPT) is a method for experimentally reconstructing the quantum channel from measurement data.

A QPT experiment prepares multiple input states, evolves them by the circuit, then performs multiple measurements in different measurement bases. The resulting measurement data is then post-processed by a tomography fitter to reconstruct the quantum channel.

Analysis class reference

ProcessTomographyAnalysis

Experiment options

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

Options

• Defined in the class TomographyExperiment:

  • basis_indices (Iterable[Tuple[List[int], List[int]]])

    Default value: None

    The basis elements to be measured. If None All basis elements will be measured.

• 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.

Note

Performing full process tomography on an N-qubit circuit requires running $4^N{3}^N$ measurement circuits when using the default preparation and measurement bases.

See also

• Superclass qiskit_experiments.library.tomography.tomography_experiment.TomographyExperiment

Initialization

Initialize a quantum process tomography experiment.

Parameters:

• circuit (Union[QuantumCircuit, Instruction, BaseOperator]) – the quantum process circuit. If not a quantum circuit it must be a class that can be appended to a quantum circuit.

• backend (Optional[Backend]) – The backend to run the experiment on.

• physical_qubits (Optional[Sequence[int]]) – Optional, the physical qubits for the initial state circuit. If None this will be qubits [0, N) for an N-qubit circuit.

• measurement_basis (MeasurementBasis) – Tomography basis for measurements. If not specified the default basis is the PauliMeasurementBasis.

• measurement_indices (Optional[Sequence[int]]) – Optional, the physical_qubits indices to be measured. If None all circuit physical qubits will be measured.

• preparation_basis (PreparationBasis) – Tomography basis for measurements. If not specified the default basis is the PauliPreparationBasis.

• preparation_indices (Optional[Sequence[int]]) – Optional, the physical_qubits indices to be prepared. If None all circuit physical qubits will be prepared.

• basis_indices (Optional[Sequence[Tuple[List[int], List[int]]]]) – Optional, a list of basis indices for generating partial tomography measurement data. Each item should be given as a pair of lists of preparation and measurement basis configurations ([p[0], p[1], ..], m[0], m[1], ...]), where p[i] is the preparation basis index, and m[i] is the measurement basis index for qubit-i. If not specified full tomography for all indices of the preparation and measurement bases will be performed.

• conditional_circuit_clbits (Union[bool, Sequence[int], Sequence[Clbit]]) – Optional, the clbits in the source circuit to be conditioned on when reconstructing the channel. If True all circuit clbits will be conditioned on. Enabling this will return a list of reconstrated channel components conditional on the values of these clbit values.

• analysis (Union[BaseAnalysis, None, str]) – Optional, a custom analysis instance to use. If "default" ProcessTomographyAnalysis will be used. If None no analysis instance will be set.

• target (Union[Statevector, DensityMatrix, None, str]) – Optional, a custom quantum state target for computing the state fidelity of the fitted density matrix during analysis. If “default” the state will be inferred from the input circuit if it contains no classical instructions.

Attributes

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

Methods

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