XanaduAI/thewalrus: Version 0.15.0

New features Adds the function random_banded_interferometer to generate unitary matrices with a given bandwidth. #208 Adds the function tvd_cutoff_bounds to calculate bounds in the total variation distance between a Fock-truncated and an ideal GBS distribution. #210 Adds function for calculating threshold detection probabilities for Gaussian states with displacement. #220 Adds new functions total_photon_number_distribution and characteristic_function to study properties of the total photon number distribution of a k identical lossy squeezers. #230 Adds new functions xxpp_to_xpxp and xpxp_to_xxpp in the symplectic module to swap the ordering of the quadrature operators in vectors and matrices. #237 Improvements The hafnians and loop hafnians of diagonal matrices are now calculated in polynomial time. #212 Refactors setup.py to avoid issues with CFLAGS. #229 The fidelity function in quantum/gaussian_checks.py is rewritten to add clarity. #226 Simplifies logic of normal_ordered_expectation by removing mutually cancelling np.conj. #228 Bug fixes Removes unnecessary np.real_if_close statements in quantum/fock_tensors.py causing the probabilities to not be normalized. #215 Fixes the prefactor in pure_state_amplitude. #231 Contributors This release contains contributions from (in alphabetical order): Jack Brown, Jake Bulmer, Rachel Chadwick, Stefano Paesani, Nicolas Quesad