channel_metrics.completely_bounded_spectral_norm

Computes the completely bounded spectral norm of a quantum channel.

Functions

completely_bounded_spectral_norm(phi)

Compute the completely bounded spectral norm of a quantum channel.

Module Contents

channel_metrics.completely_bounded_spectral_norm.completely_bounded_spectral_norm(phi)

Compute the completely bounded spectral norm of a quantum channel.

As defined in [1] and [2].

Examples

To computer the completely bounded spectral norm of a depolarizing channel,

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)
completely_bounded_spectral_norm(choi_depolarizing)

1

References

[1]

John Watrous. Semidefinite programs for completely bounded norms. 2009. arXiv:0901.4709.

[2]

Nathaniel Johnston. QETLAB: A MATLAB toolbox for quantum entanglement. URL: https://github.com/nathanieljohnston/QETLAB, doi:10.5281/zenodo.44637.

Parameters:

phi (numpy.ndarray) – superoperator

Returns:

The completely bounded spectral norm of the channel

Return type:

float