cirq.depolarize

Returns a DepolarizingChannel with given probability of error.

Used in the notebooks

This channel applies one of 4n disjoint possibilities: nothing (the identity channel) or one of the 4n1 pauli gates. The disjoint probabilities of the non-identity Pauli gates are all the same, p/(4n1), and the identity is done with probability 1 - p. The supplied probability must be a valid probability or else this constructor will raise a ValueError.

This channel evolves a density matrix via

ρ(1p)ρ+p/(4n1)iPiρPi

where Pi are the 4n1 Pauli gates (excluding the identity).

p The probability that one of the Pauli gates is applied. Each of the Pauli gates is applied independently with probability p/(4n1).
n_qubits The number of qubits.

ValueError if p is not a valid probability.