Universal scaling laws for correlation spreading in quantum systems with short- and long-range interactions

The ability of many-body systems to spread out information has fundamental impact on quantum information, thermodynamics, and transport dynamics. Long-range interactions are particularly appealing as they pave the way to nonballistic dynamics, and recent observations challenge existing bounds. Here, the authors develop a general theory based on quasiparticles that unifies short-range and long-range systems. They show that, in general, two signals coexist and carry complementary information about the many-body spectrum. One of the signals is subballistic while the other may be superballistic. This result has fundamental implications on the interpretation of experiments and offers tools to probe many-body systems.