Experimental investigation, using trapped ions, of quantum correlation propagation in systems with long-range interactions

Printer-friendly versionSend by emailPDF version

Non-local propagation of correlations in quantum systems with long-range interactions
P. Richerme, Z.-X. Gong, A. Lee, C. Senko, J. Smith, M. Foss-Feig, S. Michalakis, A. V. Gorshkov, C. Monroe
Nature 511, 198-201 (2014);
Quasiparticle engineering and entanglement propagation in a quantum many-body system
P. Jurcevic, B. P. Lanyon, P. Hauke, C. Hempel, P. Zoller, R. Blatt, C. F. Roos Nature 511, 202-205 (2014)

The maximum speed with which information can propagate in a quantum many-body system directly affects how quickly distant parts of the system can become correlated. For systems with only short-range interactions, Lieb and Robinson derived a constant-velocity bound that limits correlations to within a linear effective ‘light cone’. However, little is known about the propagation speed in systems with long-range interactions, since analytic solutions rarely exist and the best long-range bound is too loose to accurately describe the relevant dynamical timescales for any known spin model.

Both of these works report the experimental investigation using trapped ions of quantum correlation propagation in systems with long-range interactions. In the first work, Richerme and co-workers apply a variable-range Ising spin chain Hamiltonian and a variable-range XY spin chain Hamiltonian to a far-from- equilibrium quantum many-body system and observe its time evolution. For several different interaction ranges, they determine the spatial and time-dependent correlations, extract the shape of the light cone and measure the velocity with which correlations propagate through the system.

In the second work, Jurcevic and co-workers implement a similar experiment. Using the ability to tune the interaction range in trapped ion systems, they also study the information propagation in systems with long- range interactions.

These two works open the possibility for studying a wide range of new many-body dynamics of interacting quantum systems.