# cirq.PhaseDampingChannel¶

class cirq.PhaseDampingChannel(gamma)[source]

Dampen qubit phase.

This channel models phase damping which is the loss of quantum
information without the loss of energy.
__init__(gamma) → None[source]

The phase damping channel.

Construct a channel that enacts a phase damping constant gamma.

This channel evolves a density matrix via:

$$\rho \rightarrow M_0 \rho M_0^\dagger + M_1 \rho M_1^\dagger$$
With:

\begin{aligned} M_0 =& \begin{bmatrix} 1 & 0 \newline 0 & \sqrt{1 - \gamma} \end{bmatrix} \newline M_1 =& \begin{bmatrix} 0 & 0 \newline 0 & \sqrt{\gamma} \end{bmatrix} \end{aligned}

Parameters: gamma – The damping constant. ValueError – if gamma is not a valid probability.

Methods

 controlled_by(*control_qubits) Returns a controlled version of this gate. num_qubits() The number of qubits this gate acts on. on(*qubits) Returns an application of this gate to the given qubits. on_each(*targets) Returns a list of operations apply this gate to each of the targets. validate_args(qubits) Checks if this gate can be applied to the given qubits. wrap_in_linear_combination(coefficient, …)