rydiqule.sensor_utils.get_rho_ij¶

rydiqule.sensor_utils.get_rho_ij(sols: ndarray | Solution, i: int, j: int) → complex | ndarray[source]¶

For a given density matrix solution, retrieve a specific element of the density matrix.

Assumes the ground state of the solution is eliminated (as per remove_ground()), and assumes Rydiqule’s nominal state ordering of the Density Vector (per make_real()).

Parameters:

sols (numpy.ndarray or Solution) – Solutions to extract the matrix element for. Can be either the solution object returned by the solve or an N-D array representing density vectors, with ground state removed, and written in the totally real equations.
i (int) – density matrix index i
j (int) – density matrix index j

Returns:

Array of rho_ij values. Will be of type float when i==j. Will be of type complex128 when i!=j.

Return type:

numpy.ndarray

Examples

>>> sols = np.arange(180).reshape((4,5,3,3))
>>> print(sols.shape)
(4, 5, 3, 3)
>>> rho_01 = rq.get_rho_ij(sols, 0,1)
>>> print(rho_01.shape)
(4, 5, 3)
>>> print(rho_01[0,0])
[0.-1.j 3.-4.j 6.-7.j]