A channel that depolarizes a qubit.
__init__(p: float) → None¶
The symmetric depolarizing channel.This channel applies one of four disjoint possibilities: nothing (theidentity channel) or one of the three pauli gates. The disjointprobabilities of the three gates are all the same, p / 3, and theidentity is done with probability 1 - p. The supplied probability mustbe a valid probability or else this constructor will raise a ValueError.
This channel evolves a density matrix via
$$ \rho \rightarrow (1 - p) \rho + (p / 3) X \rho X + (p / 3) Y \rho Y + (p / 3) Z \rho Z $$
p – The probability that one of the Pauli gates is applied. Each of the Pauli gates is applied independently with probability p / 3.
ValueError – if p is not a valid probability.