Hilbert Space Fragmentation in the Chiral Luttinger Liquid

Abstract

The chiral Luttinger liquid develops quantum chaos as soon as a -- however slight -- nonlinear dispersion is introduced for the microscopic electronic degrees of freedom. For this nonlinear version of the model, we identify an infinite family of translation-invariant interaction potentials that display increasing degrees of Hilbert space fragmentation. We corroborate this result by studying entanglement entropy and level statistics. We also develop a systematic understanding of the unconventional symmetries giving rise to fragmentation and use them to classify the possible fragmentation patterns. In particular, this approach allows us to predict the analytic block sizes and derive asymptotic scaling laws in the limit of large total momentum.