The SDP value for random two-eigenvalue CSPs

We precisely determine the SDP value (equivalently, quantum value) of large random instances of certain kinds of constraint satisfaction problems, ``two-eigenvalue 2CSPs. We show this SDP value coincides with the spectral relaxation value, possibly indicating a computational threshold. Our analysis extends the previously resolved cases of random regular $mathsf{2XOR}$ and $textsf{NAE-3SAT}$, and includes new cases such as random $mathsf{Sort}_4$ (equivalently, $mathsf{CHSH}$) and $mathsf{Forrelation}$ CSPs. Our techniques include new generalizations of the nonbacktracking operator, the Ihara--Bass Formula, and the Friedman/Bordenave proof of Alons Conjecture.