def kraus(
targets: QubitSetInput, matrices: Iterable[np.array], display_name: str = "KR"
) -> Iterable[Instruction]:
"""Registers this function into the circuit class.
Args:
targets (Qubit, int, or iterable of Qubit / int): Target qubit(s)
matrices (Iterable[np.array]): Matrices that define a general noise channel.
Returns:
Iterable[Instruction]: `Iterable` of Kraus instructions.
Examples:
>>> K0 = np.eye(4) * sqrt(0.9)
>>> K1 = np.kron([[1., 0.],[0., 1.]], [[0., 1.],[1., 0.]]) * sqrt(0.1)
>>> circ = Circuit().kraus(0, matrices=[K0, K1])
"""
if 2 ** len(targets) != matrices[0].shape[0]:
raise ValueError(
"Dimensions of the supplied Kraus matrices are incompatible with the targets"
)
return Instruction(
Noise.Kraus(matrices=matrices, display_name=display_name), target=targets
)
def noise_2qubit():
E0 = np.sqrt(0.8) * np.eye(4)
E1 = np.sqrt(0.2) * np.kron(np.array([[0, 1], [1, 0]]), np.array([[0, 1], [1, 0]]))
return Noise.Kraus(matrices=[E0, E1])
