Nicolás Quesada

Bloch-Messiah returns incorrect results

2

### Before posting a bug report - [X] I have searched exisisting GitHub issues to make sure the issue does not already exist. ### Expected behavior Consider ```python import numpy...

Rounding issue in Takagi when complex

6

When using `decomposition.takagi` there is a problem when the matrix is complex and has singular value close to zero. The funcion `takagi` has an optional argument called `rounding` which uses...

Given the results from https://quantum-journal.org/papers/q-2020-11-30-366/ it should be possible to implement natively in Fock space any Gaussian gate. Thus for example we should not need to decompose the `MZgate`, `CXgate`,...

Adds improved Bloch-Messiah that gives correct results when the symplectic matrix is degenerate

1

This is related to this issue: https://github.com/XanaduAI/strawberryfields/issues/728

Recursive calculation of threshold probabilitites

4

It would be good to find a way to calculate recursively all the click probabilities of a Gaussian state.

### Before posting a bug report - [X] I have searched exisisting GitHub issues to make sure the issue does not already exist. ### Expected behavior ```python from thewalrus.random import...

Improve presentation of sampling algorithms

2

The discussion of sampling algorithms can be greatly improved by for example following the what is done here https://arxiv.org/abs/1908.08068

[unitaryhack] Improve the calculation of multidimensional hermite polynomials

10

*This issue has been tagged for a bounty during [unitaryHACK](https://unitaryfund.github.io/unitaryhack/participating-projects.html)* Currently all calculations of [multidimensional hermite polynomials](https://the-walrus.readthedocs.io/en/latest/hermite.html) are carried in `double` precision even though the [C++ functions](https://github.com/XanaduAI/thewalrus/blob/master/include/hermite_multidimensional.hpp) to do these...

The functionality to generate random Haar unitary and orthogonal matrices is already implemented in scipy as [`unitary_group`](https://docs.scipy.org/doc/scipy/reference/generated/scipy.stats.unitary_group.html) and [`ortho_group`](https://docs.scipy.org/doc/scipy/reference/generated/scipy.stats.ortho_group.html). We should just use this functionality inside `random_interferometer` instead of reinventing...

New states in The Walrus gallery

1

There are a number of non-Gaussian state preparations that would make nice additions to The Walrus gallery: * NOON and W states from https://arxiv.org/abs/1902.02323 * GKP states from https://arxiv.org/abs/1910.03673