Entanglement fidelity between two unitaries.

For unitary matrices, this is related to the average unitary fidelity F as

:math:F = \frac{F_e d + 1}{d + 1} where d is the matrix dimension.

U_actual Matrix whose fidelity to U_ideal will be computed. This may be a non-unitary matrix, i.e. the projection of a larger unitary matrix into the computational subspace.
U_ideal Unitary matrix to which U_actual will be compared.

Both arguments may be vectorized, in that their shapes may be of the form (...,M,M) (as long as both shapes can be broadcast together).

The entanglement fidelity between the two unitaries. For inputs with shape (...,M,M), the output has shape (...).