Author(s): Amir-Reza Negari and Farzin Salek We investigate $({k}_{1},{k}_{2})$ extendibility of fermionic Gaussian states, a property central to quantum correlations and approximations of separability. We show that these states are $({k}_{1},{k}_{2})$-extendible if and only if they admit a fermionic Gaussian extension, yielding a complete cov… [Phys. Rev. Lett. 137, 080201] Published Tue Aug 18, 2026