Fermionic Gaussian Scrooge Ensembles in Deep Thermalization
The fermionic Gaussian Scrooge ensemble describes deep thermalization in free-fermion systems by distorting the Gaussian Haar ensemble with an average density matrix. This universal ensemble emerges in both SYK2 model dynamics and random Gaussian circuits, revealing an enlarged symmetry of Gaussian states. It provides a general framework for characterizing thermalization in these systems.