ffsim.random.random_density_matrix

ffsim.random.random_density_matrix(dim, *, seed=None, dtype=<class 'complex'>)

Returns a random density matrix distributed with Hilbert-Schmidt measure.

A density matrix is positive semi-definite and has trace equal to one.

Parameters:

• dim (int) – The width and height of the matrix.

• seed – A seed to initialize the pseudorandom number generator. Should be a valid input to np.random.default_rng.

Return type:

ndarray

Returns:

The sampled density matrix.

Raises:

ValueError – Dimension must be at least one.

References

• Osipov, Sommers, and Zyczkowski, “Random Bures mixed states and the distribution of their purity” (2010)