Weak ergodicity breaking from supersymmetry in a fermionic kinetically constrained model

Abstract: Supersymmetry provides a natural playground for the construction of kinetically constrained lattice fermion models showing weak ergodicity breaking. The supersymmetric algebra naturally induces non-ergodic dynamics, as we illustrate here by introducing a fermionic equivalent of the PXP model with an adjustable chemical potential. This model is closely related to the $\mathcal{N} = 2$ supersymmetric $M_1$ model. Supersymmetry directly implies that the dynamics exhibit periodic revivals for specific initial states, including the $\mathbb{Z}_2$-ordered (every second site occupied) product state. These dynamics are reminiscent to those of the PXP model, a paradigmatic toy model in the field of quantum many-body scars. We draw a further parallel by uncovering quantum many-body scar-like eigenstates obeying sub-thermal entanglement scaling at energies given by (plus or minus) square roots of integers and relate these to special eigenstates of the $M_1$ model.