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.

StateTomography

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

An experiment to reconstruct the quantum state from measurement data.

Overview

Quantum state tomography (QST) is a method for experimentally reconstructing the quantum state from measurement data.

A QST experiment measures the state prepared by quantum circuit in different measurement bases and post-processes the measurement data to reconstruct the state.

Analysis class reference

StateTomographyAnalysis

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 state tomography on an N-qubit state requires running $3^N$ measurement circuits when using the default measurement basis.

See also

• Superclass qiskit_experiments.library.tomography.tomography_experiment.TomographyExperiment

Initialization

Initialize a quantum process tomography experiment.

Parameters:

• circuit (Union[QuantumCircuit, Instruction, BaseOperator, Statevector]) – 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.

• basis_indices (Optional[Sequence[List[int]]]) – Optional, a list of basis indices for generating partial tomography measurement data. Each item should be given as a list of measurement basis configurations [m[0], m[1], ...] where m[i] is the measurement basis index for qubit-i. If not specified full tomography for all indices of the measurement basis 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 state. If True all circuit clbits will be conditioned on. Enabling this will return a list of reconstrated state components conditional on the values of these clbit values.

• analysis (Union[BaseAnalysis, None, str]) – Optional, a custom analysis instance to use. If "default" StateTomographyAnalysis 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

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

Methods

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