Estimating T2 decoherence times

We estimate the T2 time based on experiment results from t2_circuits executed on noisy devices. The estimate is based on the probability formula of measuring 0 from the following equation, where A, T2, and B are unknown parameters:

Finally, to estimate T2* and characterize the qubit with respect to the results, we will leverage T2Fitter. To generate the T2Fitter class, we will use similar parameter definitions as T1Fitter in the previous section, only this time, we will use the results from the T2 test circuits:

# Generate the T2Fitter class using similar parameters as the # T1Fitter
t2echo_fit = T2Fitter(t2echo_backend_result, t2echo_delay_times, qubits, fit_p0=[0.5, t2, 0.5], fit_bounds=([-0.5, 0, -0.5], [1.5, 40, 1.5]))
# Print and plot the results
print(t2echo_fit.params) 
t2echo_fit.plot(0)
plt.show()

The preceding code prints out the estimate values for A, T2, and B for qubit 0:

{'0': [array([ 0.52397653, 27.06685838,...