Many-body localization in a quantum simulator with programmable random disorder

Abstract

When a system thermalizes it loses all memory of its initialconditions. Even within a closed quantum system, subsystemsusually thermalize using the rest of the system as a heat bath.Exceptions to quantum thermalization have been observed,but typically require inherent symmetries^1,2or noninteractingparticles in the presence of static disorder^3–6. However, forstrong interactions and high excitation energy there are cases,known as many-body localization (MBL), where disorderedquantum systems can fail to thermalize^7–10. We experimentallygenerate MBL states by applying an Ising Hamiltonian withlong-range interactions and programmable random disorder toten spins initialized far from equilibrium. Using experimentaland numerical methods we observe the essential signaturesof MBL: initial-state memory retention, Poissonian distributedenergy level spacings, and evidence of long-time entanglementgrowth. Our platform can be scaled to more spins, where adetailed modelling of MBL becomes impossible.