iqm.error_reduction_tools.readout_characterization.data_processing.compute_single_twirled_covariance

iqm.error_reduction_tools.readout_characterization.data_processing.compute_single_twirled_covariance(data)

Compute single-twirled readout error correlations between qubit pairs.

Calculates covariances where one qubit has a state-dependent error (conditioned on its preparation) and the other has a preparation-averaged (twirled) error. This reveals correlations that persist regardless of the second qubit’s state.

Parameters:

data (CalibrationData) – Calibration data from run_calibration_circuits().

Returns:

Single- and double-twirled covariance output.

Return type:

SingleCovarianceData

Note

Error IDs match _get_error_ids_for_shot() encoding (0=00, 1=11, 2=01, 3=10). Correlation[i,j] = P(error_i, syndrome_j) - P(error_i)P(syndrome_j)