cirq.phase_flip

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Returns a PhaseFlipChannel that flips a qubit's phase with probability p.

cirq.phase_flip(
    p: Optional[float] = None
) -> Union[cirq.ZPowGate, cirq.PhaseFlipChannel]

Used in the notebooks

If p is None, return a guaranteed phase flip in the form of a Z operation.

This channel evolves a density matrix via:

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

With:

$$\begin{aligned} M_0 =& \sqrt{1 - p} \begin{bmatrix} 1 & 0 \\ 0 & 1 \end{bmatrix} \\ M_1 =& \sqrt{p} \begin{bmatrix} 1 & 0 \\ 0 & -1 \end{bmatrix} \end{aligned}$$