DepolarizingChannel

DepolarizingChannel is a function that returns the Choi matrix of the partially depolarizing channel, which acts as follows:


 * $$\Delta(X) := (1-p)\mathrm{Tr}(X)\frac{I}{d^2} + pX,$$

where $I$ is the identity matrix, $d$ is the local dimension, and $0 \leq p \leq 1$ is a given parameter ($p = 0$ by default).

Syntax

 * DELTA = DepolarizingChannel(DIM)
 * DELTA = DepolarizingChannel(DIM,P)

Argument descriptions

 * DIM: The dimension of the channel. That is, the channel will act on DIM-by-DIM matrices.
 * P (optional, default 0): A parameter (from 0 to 1, inclusive) that specifies which partially depolarizing channel to produce. P = 0 gives the completely depolarizing channel, and P = 1</tt> gives the identity channel.

The completely depolarizing channel
The completely depolarizing channel maps every density matrix to the maximally-mixed state: