toqito.channel_metrics.completely_bounded_spectral_norm

Computes the completely bounded spectral norm of a quantum channel.

Module Contents

toqito.channel_metrics.completely_bounded_spectral_norm.completely_bounded_spectral_norm(phi)

Compute the completely bounded spectral norm of a quantum channel.

As defined in [@Watrous_2009_Semidefinite] and [@QETLAB_link].

Examples

To compute the completely bounded spectral norm of a depolarizing channel:

`python exec="1" source="above" from toqito.channels import depolarizing from toqito.channel_metrics import completely_bounded_spectral_norm # Define the depolarizing channel choi_depolarizing = depolarizing(dim=2, param_p=0.2) print(completely_bounded_spectral_norm(choi_depolarizing)) `

Parameters:

phi (numpy.ndarray) – superoperator

Returns:

The completely bounded spectral norm of the channel

Return type:

float | numpy.floating