Cartan decomposition does not work for random unitaries

[goerz]

The Cartan decomposition works for "standard gates" but fails for random unitaries, via this test:

weylchamber/tests/test_cartan_decomposition.py

Line 10 in 43cf503

@pytest.mark.xfail

@danielreich When we wrote this routine back in the day, I remember us testing this rather extensively. So, I don't know why it's failing now. It's in no way urgent to fix this, but at some point we should look into this again.

[pranavm1502]

Hi,
Firstly, thank you for making this amazing package so user-friendly!

I am a graduate student working with Andrew Houck at Princeton University. We were planning to use your package for some simulations. Is the Cartan decomposition of arbitrary gates, still an unfixed issue?

[goerz]

Yes, it's still unfixed. If you're actively using Cartan decomposition and you find that you're affected by this bug, you might be able to find out what's wrong here. Neither me nor @danielreich are currently using this code in any active research, so we'll probably not be able to look into this in the short term.

@Basilewitsch: Do you have any ideas, maybe?