Quantum Many-Body Scars from Einstein-Podolsky-Rosen States in Bilayer Systems

TL;DR

This paper introduces a new framework for understanding quantum many-body scar states as arising from maximally entangled EPR states in bilayer systems, unifying several known examples and revealing new scar states.

Contribution

It presents a novel construction of scar states from EPR states in bilayer systems, applicable to various models including spin, fermions, and bosons, and demonstrates its versatility and implications.

Findings

Unifies known scar states like the XY model tower and η-pairing states under a common formalism.

Shows how symmetries enhance the construction's applicability.

Predicts an infinite tower of scar states in bilayer Bose-Hubbard models.

Abstract

Quantum many-body scar states are special eigenstates of nonintegrable models with distinctive entanglement features that give rise to infinitely long-lived coherent dynamics under quantum quenches from certain initial states. We elaborate on a construction of quantum many-body scar states in which they emerge from Einstein-Podolsky-Rosen (EPR) states in systems with two layers, wherein the two layers are maximally entangled. We apply this construction to spin systems as well as systems of itinerant fermions and bosons and demonstrate how symmetries can be harnessed to enhance its versatility. We show that several well-known examples of quantum many-body scars, including the tower of states in the spin-1 XY model and the $\eta$-pairing states in the Fermi-Hubbard model, can be understood within this formalism. We also demonstrate how an {\it infinite} tower of many-body scar states can emerge in bilayer Bose-Hubbard models with charge conservation.