Unconventional Transport in a System with a Tower of Quantum Many-Body Scars

Abstract: We report the observation of unconventional transport phenomena in a spin-1 model that supports a tower of quantum many-body scars, and we discuss their properties uncovering their peculiar nature. In quantum many-body systems, the late-time dynamics of local observables are typically governed by conserved operators with local densities, such as energy and magnetization. In the model under investigation, however, there is an additional dynamical symmetry restricted to the subspace of the Hilbert space spanned by the quantum many-body scars. That significantly slows the decay of autocorrelation functions of certain coherent states and is responsible for an unconventional form of transport. We show that excited states with energy close to that of the quantum many-body scars play a crucial role in sustaining the transport; counterintuitively, quantum many-body scars are completely irrelevant for the aforementioned mechanism. Finally, we propose a generalized eigenstate thermalization hypothesis to describe specific properties of states with energy close to the scars.