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.

T2Hahn¶

class T2Hahn(physical_qubits, delays, num_echoes=1, backend=None)[source]¶

An experiment to measure the dephasing time insensitive to inhomogeneous broadening using Hahn echos.

Overview

This experiment is used to estimate the $T_{2}$ time of a single qubit. $T_{2}$ 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 T2Ramsey, $T_{2}$ is insensitive to inhomogenous broadening.

This experiment consists of a series of circuits of the form

     ┌─────────┐┌──────────┐┌───────┐┌──────────┐┌─────────┐┌─┐
q_0: ┤ Rx(π/2) ├┤ DELAY(t) ├┤ RX(π) ├┤ DELAY(t) ├┤ RX(π/2) ├┤M├
     └─────────┘└──────────┘└───────┘└──────────┘└─────────┘└╥┘
c: 1/════════════════════════════════════════════════════════╩═
                                                             0

for each t from the specified delay times and the delays are specified by the user. The delays that are specified are delay for each delay gate while the delay in the metadata is the total delay which is delay * (num_echoes +1) 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 Hahn Characterization

Analysis class reference

T2HahnAnalysis

Experiment options

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

Options

Defined in the class T2Hahn:
- delays (Iterable[float])
  
  Default value: None
  
  Delay times of the experiments.
- num_echoes (int)
  
  Default value: 1
  
  The number of echoes to preform.
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 T2 - Hahn Echo class

Parameters:

physical_qubits (Sequence[int]) – a single-element sequence containing the qubit whose T2 is to be estimated
delays (Union[List[float], array]) – Total delay times of the experiments.
backend (Optional[Backend]) – Optional, the backend to run the experiment on.
num_echoes (int) – The number of echoes to preform.
backend –
Optional, the backend to run the experiment on.

Raises:
QiskitError : Error for invalid input.

Attributes

`T2Hahn.analysis`	Return the analysis instance for the experiment
`T2Hahn.backend`	Return the backend for the experiment
`T2Hahn.experiment_options`	Return the options for the experiment.
`T2Hahn.experiment_type`	Return experiment type.
`T2Hahn.num_qubits`	Return the number of qubits for the experiment.
`T2Hahn.physical_qubits`	Return the device qubits for the experiment.
`T2Hahn.run_options`	Return options values for the experiment `run()` method.
`T2Hahn.transpile_options`	Return the transpiler options for the `run()` method.

Methods

`T2Hahn.circuits`()	Return a list of experiment circuits.
`T2Hahn.config`()	Return the config dataclass for this experiment
`T2Hahn.copy`()	Return a copy of the experiment
`T2Hahn.from_config`(config)	Initialize an experiment from experiment config
`T2Hahn.run`([backend, analysis, timeout])	Run an experiment and perform analysis.
`T2Hahn.set_experiment_options`(**fields)	Set the experiment options.
`T2Hahn.set_run_options`(**fields)	Set options values for the experiment `run()` method.
`T2Hahn.set_transpile_options`(**fields)	Set the transpiler options for `run()` method.