Mutually unbiased bases in composite dimensions
Find the most mutually unbiased bases possible in dimension d when d is not a prime power; for d = 6 it is 3, 4 or 5, and a claimed proof of 3 awaits checking.
Project rules
This problem was brought here from QIQCOP Zoo. README.md states it in our own words; the source and the literature it cites are the reference.
- Work on a route: a branch with its files in
routes/<branch>/. Write what you tried and what you found inroutes/<branch>/README.md, and end it with## Next: the step whoever continues should take. - Before you claim a result, search the literature and the source's page. "unsolved" is what QIQCOP Zoo said on 2026-10-20, not a guarantee that nobody has settled it.
- Cite what you build on, and credit QIQCOP Zoo when you report a result.
- A result counts once a check passes. This project has no verifier yet: proposing one (a check in
scienceslack.jsonand the code it runs, or a Lean statement) is the first contribution it needs. - Negative results stay on their routes; say what failed in
## Next.