Content area
Full Text
LETTERS
PUBLISHED ONLINE: 6 JUNE 2016 | DOI: http://dx.doi.org/10.1038/nphys3783
Web End =10.1038/NPHYS3783
Many-body localization in a quantum simulator with programmable random disorder
J. Smith1*, A. Lee1, P. Richerme2, B. Neyenhuis1, P. W. Hess1, P. Hauke3,4, M. Heyl3,4,5, D. A. Huse6
and C. Monroe1
When a system thermalizes it loses all memory of its initial conditions. Even within a closed quantum system, subsystems usually thermalize using the rest of the system as a heat bath. Exceptions to quantum thermalization have been observed, but typically require inherent symmetries1,2 or noninteracting particles in the presence of static disorder36. However, for strong interactions and high excitation energy there are cases, known as many-body localization (MBL), where disordered quantum systems can fail to thermalize710. We experimentally
generate MBL states by applying an Ising Hamiltonian with long-range interactions and programmable random disorder to ten spins initialized far from equilibrium. Using experimental and numerical methods we observe the essential signatures of MBL: initial-state memory retention, Poissonian distributed energy level spacings, and evidence of long-time entanglement growth. Our platform can be scaled to more spins, where a detailed modelling of MBL becomes impossible.
It is exceedingly rare in nature for systems to localize, or retain local information about their initial conditions at long times. In an important counterexample, Anderson demonstrated that localization can arise due to the presence of disorder, which can destructively scatter propagating waves and prevent transport of energy or particles3. Although this interference eect can be applied to generic quantum systems, most experimental work has been restricted to the narrow parameter regime of low excitation energies and no interparticle interactions46.
Whether such localization persists in the more general case of arbitrary excitation energy and non-zero interparticle interactions was theoretically explored by Anderson3, and more recently by others710. This MBL phase is predicted to emerge for a broad set of interaction ranges and disorder strengths, although the precise phase diagram is not well known11 because equilibrium statistical mechanics breaks down in the MBL phase and numerical simulations are limited to 20 particles8,9. Very recent experiments searching for
MBL have measured constrained mass transport and the breakdown of ergodicity in disordered atomic systems with interactions12,13.
Here we report the direct observation of MBL in a long-range transverse field Ising model with programmable,...