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.

T2Ramsey

class T2Ramsey(physical_qubits, delays, backend=None, osc_freq=0.0)

An experiment to measure the Ramsey frequency and the qubit dephasing time sensitive to inhomogeneous broadening.

Overview

This experiment is used to estimate two properties for a single qubit: $T_2^{\ast }$ and Ramsey frequency. $T_2^{\ast }$ is the dephasing time or the transverse relaxation time of the qubit on the Bloch sphere as a result of both energy relaxation and pure dephasing in the transverse plane. Unlike $T_2$, which is measured by T2Hahn, $T_2^{\ast }$ is sensitive to inhomogenous broadening.

This experiment consists of a series of circuits of the form

     ┌───┐┌──────────────┐┌──────┐ ░ ┌───┐ ░ ┌─┐
q_0: ┤ H ├┤   DELAY(t)   ├┤ P(λ) ├─░─┤ H ├─░─┤M├
     └───┘└──────────────┘└──────┘ ░ └───┘ ░ └╥┘
c: 1/═════════════════════════════════════════╩═
                                            0

for each t from the specified delay times, where $\lambda =2\pi \times osc\mathrm{\_}freq$, and the delays are specified by the user. The circuits are run on the device or on a simulator backend.

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

T2* Ramsey Characterization

Analysis class reference

T2RamseyAnalysis

Experiment options

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

Options

• Defined in the class T2Ramsey:

  • delays (Iterable[float])

    Default value: None

    Delay times of the experiments in seconds.

  • osc_freq (float)

    Default value: 0.0

    Oscillation frequency offset in Hz.

• 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 the T2Ramsey class.

Parameters:

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

• delays (Union[List[float], array]) – delay times of the experiments in seconds.

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

• osc_freq (float) – the oscillation frequency induced by the user. The frequency is given in Hz.

Attributes

T2Ramsey.analysis	Return the analysis instance for the experiment
T2Ramsey.backend	Return the backend for the experiment
T2Ramsey.experiment_options	Return the options for the experiment.
T2Ramsey.experiment_type	Return experiment type.
T2Ramsey.num_qubits	Return the number of qubits for the experiment.
T2Ramsey.physical_qubits	Return the device qubits for the experiment.
T2Ramsey.run_options	Return options values for the experiment run() method.
T2Ramsey.transpile_options	Return the transpiler options for the run() method.

Methods

T2Ramsey.circuits()	Return a list of experiment circuits.
T2Ramsey.config()	Return the config dataclass for this experiment
T2Ramsey.copy()	Return a copy of the experiment
T2Ramsey.from_config(config)	Initialize an experiment from experiment config
T2Ramsey.run([backend, analysis, timeout])	Run an experiment and perform analysis.
T2Ramsey.set_experiment_options(**fields)	Set the experiment options.
T2Ramsey.set_run_options(**fields)	Set options values for the experiment run() method.
T2Ramsey.set_transpile_options(**fields)	Set the transpiler options for run() method.