Conjectured bijection between SIC-POVMs and ring class monoid elements
Prove the conjectured bijection between SIC-POVMs in dimension d and the elements of the ideal class monoid \(\Clmpa(\mathcal{O})\) for the quadratic order \(\mathcal{O}=\mathbb{Z}[\frac{d-1+\sqrt{(d+1)(d-3)}}{2}]\).
References
SIC-POVMs, or generalized quantum measurements described by configurations of $d2$ equiangular complex lines in $\Cd$, are conjectured to be in bijection with the elements of $\Clmpa(\OO)$ for $\OO = \Z!\left[\frac{d-1+\sqrt{(d+1)(d-3)}{2}\right]$.
— Ray class monoids for orders of number fields
(2610.11353 - Kopp, 8 Oct 2026) in Section 1, subsection 1.3 (Contents of paper); reiterated in Section 8, Section 8 (Concluding remarks)