Channels

QBase.Channels — Module

The Channels submodule provides:

A catalog of functions which apply common quantum channels to quantum states.

QBase.Channels.depolarizing — Function

depolarizing( ρ :: AbstractDensityMatrix, μ :: Real ) :: DensityMatrix

The depolarizing channel mixes uniform classical noise into a quantum state ρ. The argument μ describes the amount of noise mixed into the quantum states. For a quantum state $\rho$, the depolarizing channel is expressed:

\[ \mathcal{D}_{\mu}(\rho) = \mu \rho + \frac{(1 - \mu)}{d}\mathbb{I}\]

A DomainError is thrown if μ does not satisfy 1 ≥ μ ≥ 0.

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QBase.Channels.erasure — Function

erasure( ρ :: AbstractDensityMatrix, μ :: Real ) :: DensityMatrix

The erasure channel mixes a quantum state ρ with an error flag $|F\rangle$ orthogonal to the Hilbert space of ρ. The argument μ describes the probability that ρ is replaced with the error flag. For a quantum state $\rho$, the erasure channel is expressed:

\[ \mathcal{E}_{\mu}(\rho) = \mu \rho + (1 - \mu) |F \rangle \langle F|\]

Note that the erasure channel increases the dimension of the Hilbert space by 1.

A DomainError is thrown if μ does not satisfy 1 ≥ μ ≥ 0.

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