scqubits.TunableTransmon.plot_t2_effective_vs_paramvals#

TunableTransmon.plot_t2_effective_vs_paramvals(param_name, param_vals, noise_channels=None, common_noise_options=None, spectrum_data=None, get_rate=False, scale=1, num_cpus=None, **kwargs)#

Plot effective \(T_2\) coherence time (rate) as a function of changing parameter.

The effective \(T_2\) is calculated from both pure dephasing channels, as well as depolarization channels, according to the formula:

\[\frac{1}{T_{2}^{\rm eff}} = \sum_k \frac{1}{T_{\phi}^{k}} + \frac{1}{2} \sum_j \frac{1}{T_{1}^{j}}\]

where \(k\) (\(j\)) run over the relevant pure dephasing ( depolarization) channels that can contribute to the effective noise. By default all noise channels given by the method effective_noise_channels are included.

For example, assuming qubit is a qubit object with flux being one of its parameters, one can see how the effective \(T_2\) varies as the flux changes:

qubit.plot_t2_effective_vs_paramvals(param_name='flux',
                                     param_vals=np.linspace(-0.5, 0.5, 100),
                                    );
Parameters:

  • param_name (str) – name of parameter to be varied

  • param_vals (ndarray) – parameter values to be plugged in

  • noise_channels (Union[str, List[str], List[Tuple[str, Dict]], None]) – channels to be plotted, if None then noise channels given by supported_noise_channels are used

  • common_noise_options (Optional[Dict]) – common options used when calculating coherence times

  • spectrum_data (Optional[SpectrumData]) – spectral data used during noise calculations

  • get_rate (bool) – determines if rate or time should be plotted

  • scale (float) – a number that all data is multiplied by before being plotted

  • num_cpus (Optional[int]) – number of cores to be used for computation

Return type:

Figure, Axes