cirq.kron_factor_4x4_to_2x2s

cirq.kron_factor_4x4_to_2x2s(matrix: numpy.ndarray, tolerance: cirq.linalg.tolerance.Tolerance = Tolerance(rtol=1e-05, atol=1e-08, equal_nan=False)) → Tuple[complex, numpy.ndarray, numpy.ndarray][source]

Splits a 4x4 matrix U = kron(A, B) into A, B, and a global factor.

Requires the matrix to be the kronecker product of two 2x2 unitaries.
Requires the matrix to have a non-zero determinant.
Parameters:
  • matrix – The 4x4 unitary matrix to factor.
  • tolerance – Acceptable numeric error thresholds.
Returns:

A scalar factor and a pair of 2x2 unit-determinant matrices. The kronecker product of all three is equal to the given matrix.
Raises:

ValueError – The given matrix can’t be tensor-factored into 2x2 pieces.