T2StarFitter

class T2StarFitter(backend_result, xdata, qubits, fit_p0, fit_bounds, time_unit='micro-seconds')

Estimate T₂^*, based on experiments outcomes.

The experiments were created by t2star_circuits, and executed on the device.

The probabilities of measuring 0 is assumed to be of the form

\[f(t) = A\mathrm{e}^{-t / T_2^*}\cos(2\pi ft + \phi) + B\]

for unknown parameters \(A, B, f, \phi, T_2^*\).

Parameters

• backend_result (Result) – result of execution of t2star_circuits on the backend.

• xdata (Union[List[float], array]) – delay times of the T₂^* circuits.

• qubits (List[int]) – indices of the qubits whose T₂:sup:* ‘s are to be measured.

• fit_p0 (List[float]) – initial values to the fit parameters, where the order is \((A, T_2^*, f, \phi, B)\).

• fit_bounds (Tuple[List[float], List[float]]) – bounds on the parameters to fit. The first tuple is the lower bounds, in the order \((A, T_2^*, f, \phi, B)\). The second tuple is the upper bounds.

• time_unit (str) – unit of delay times in xdata.

Attributes

T2StarFitter.backend_result	Return the execution results
T2StarFitter.description	Return the fitter’s purpose, e.g.
T2StarFitter.fit_fun	Return the function used in the fit, e.g.
T2StarFitter.measured_qubits	Return the indices of the qubits to be characterized
T2StarFitter.params	Return the fit function parameters that were calculated by curve_fit
T2StarFitter.params_err	Return the error of the fit function parameters
T2StarFitter.series	Return the list of series for the data
T2StarFitter.xdata	Return the data points on the x-axis, the independenet parameter which is fit against
T2StarFitter.ydata	Return the data points on the y-axis

Methods

T2StarFitter.add_data(results[, recalc, refit])	Add new execution results to previous execution results
T2StarFitter.fit_data([qid, p0, bounds, series])	Fit the curve.
T2StarFitter.guess_params([qind])	Guess fit parameters for oscillation data
T2StarFitter.plot(qind[, series, ax, show_plot])	Plot coherence data.
T2StarFitter.time([qid, series])	Return the characteristic time for the given qubit and series
T2StarFitter.time_err([qid, series])	Return the error of characteristic time for the given qubit and series