Derived equivalences of twisted supersingular K3 surfaces

Abstract: We study the derived categories of twisted supersingular K3 surfaces. We prove a derived crystalline Torelli theorem for twisted supersingular K3 surfaces, characterizing Fourier-Mukai equivalences in terms of isomorphisms between their associated K3 crystals. This is a positive characteristic analog of the Hodge-theoretic derived Torelli theorem of Orlov, and its extension to twisted K3 surfaces by Huybrechts and Stellari. We give applications to various questions concerning Fourier-Mukai partners, extending results of C\u{a}ld\u{a}raru and Huybrechts and Stellari. We also give an exact formula for the number of twisted Fourier-Mukai partners of a twisted supersingular K3 surface.