Feedback-controlled dynamics in a two-dimensional array of active elements.

We investigate collective behaviors in a two-dimensional array of active elements controlled by time-delayed feedback, where elements are prepared by localizing the Belousov-Zhabotinsky reaction in a gel matrix. We demonstrate that both the spatial and temporal coherence can be effectively controlled by varying feedback parameters, such as the time delay and the gain. For a sufficiently high feedback gain, the fully synchronized state with low temporal coherence appears, which might be the state induced only by the delay feedback. Experimental results are approximately reproduced in a numerical simulation with a forced Oregonator reaction-diffusion model.