toqito.channels.phase_damping¶

phase damping channel.

Module Contents¶

toqito.channels.phase_damping.phase_damping(input_mat=None, gamma=0)[source]¶

Apply the phase damping channel to a quantum state [@Chuang_2011_Quantum].

The phase damping channel describes how quantum information is lost due to environmental interactions, causing dephasing in the computational basis without losing energy.

The Kraus operators for the phase damping channel are:

[: K_0 = begin{pmatrix} 1 & 0 \ 0 & sqrt{1 - gamma} end{pmatrix}, \ K_1 = begin{pmatrix} 0 & 0 \ 0 & sqrt{gamma} end{pmatrix},

]

Examples

Applying the phase damping channel to a qubit state:

```python exec=”1” source=”above” import numpy as np from toqito.channels.phase_damping import phase_damping

rho = np.array([[1, 0.5], [0.5, 1]]) result = phase_damping(rho, gamma=0.2)

print(result) ```

Parameters:

input_mat (numpy.ndarray | None) – The input matrix to apply the channel to. If None, the function returns the Kraus operators.
gamma (float) – The dephasing rate (between 0 and 1), representing the probability of phase decoherence.

Returns:

The transformed quantum state after applying the phase damping channel. If input_mat is None, returns the list of Kraus operators.

Return type:

numpy.ndarray | list[numpy.ndarray]