Maximal-Rank Squeezing from Rank-One Quenches: An Exact Spectral-Reachability Theorem for Gaussian Bosonic Systems

arXiv:2608.21434v1 Announce Type: new Abstract: We prove an exact spectral-reachability theorem for multimode squeezing generated by finite-rank quadratic quenches in Gaussian bosonic systems. For a stable sign-definite stiffness quench $\Omega^2 \to \Omega^2+\varepsilon U U^T$, the kernel, range,