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.

Tphi

class Tphi(physical_qubits, delays_t1, delays_t2, t2type='hahn', osc_freq=0.0, num_echoes=1, backend=None)[source]

An experiment to measure the qubit dephasing rate in the xy plane.

Overview

Tφ, or 1/Γφ, is the pure dephasing time in the xy plane of the Bloch sphere. We compute Γφ by computing Γ2, the transverse relaxation rate, and subtracting Γ1, the longitudinal relaxation rate. It follows that

1/Tφ=1/T21/2T1.

The transverse relaxation rate can be estimated by either T2 or T2 experiments. In superconducting qubits, T2 tends to be significantly smaller than T1, so T2 is usually used.

Note

In 0.5.0, this experiment changed from using T2 as the default to T2.

References

[1] Philip Krantz, Morten Kjaergaard, Fei Yan, Terry P. Orlando, Simon Gustavsson, William D. Oliver, A Quantum Engineer’s Guide to Superconducting Qubits, Applied Physics Reviews 6, 021318 (2019), doi: 10.1063/1.5089550 (open)

User manual

Tφ Characterization

Analysis class reference

TPhiAnalysis

Experiment options

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

Options
  • Defined in the class BatchExperiment:

    • separate_jobs (Boolean)

      Default value: False
      Whether to route different sub-experiments to different jobs.
  • 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.

See also

Initialization

Initialize the experiment object.

Parameters:
  • physical_qubits (Sequence[int]) – A single-element sequence containing the qubit under test.

  • t2type (str) – What type of T2/T2* experiment to use. Can be either “ramsey” for T2Ramsey to be used, or “hahn” for T2Hahn. Defaults to “hahn”.

  • delays_t1 (List[Union[List[float], array]]) – Delay times of the T1 experiment.

  • delays_t2 (List[Union[List[float], array]]) – Delay times of the T2 experiment.

  • osc_freq (float) – The oscillation frequency induced for T2Ramsey. Only used when t2type is set to “ramsey”.

  • num_echoes (int) – The number of echoes to perform for T2Hahn. Only used when t2type is set to “hahn”.

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

Raises:

QiskitError – If an invalid t2type is provided.

Attributes

Tphi.analysis

Return the analysis instance for the experiment

Tphi.backend

Return the backend for the experiment

Tphi.experiment_options

Return the options for the experiment.

Tphi.experiment_type

Return experiment type.

Tphi.num_experiments

Return the number of sub experiments

Tphi.num_qubits

Return the number of qubits for the experiment.

Tphi.physical_qubits

Return the device qubits for the experiment.

Tphi.run_options

Return options values for the experiment run() method.

Tphi.transpile_options

Return the transpiler options for the run() method.

Methods

Tphi.circuits()

Return a list of experiment circuits.

Tphi.component_experiment([index])

Return the component Experiment object.

Tphi.config()

Return the config dataclass for this experiment

Tphi.copy()

Return a copy of the experiment

Tphi.from_config(config)

Initialize an experiment from experiment config

Tphi.run([backend, analysis, timeout])

Run an experiment and perform analysis.

Tphi.set_experiment_options(**fields)

Set the experiment options.

Tphi.set_run_options(**fields)

Set options values for the experiment run() method.

Tphi.set_transpile_options(**fields)

Set the transpiler options for run() method.