We report the selective stabilization of chiral rotational direction of bacterial vortices, from turbulent bacterial suspension, in achiral circular microwells sealed by an oil-water interface. This broken-symmetry, originating from the intrinsic chirality of bacterial swimming near hydrodynamically different top and bottom surfaces, generates a chiral edge current of bacteria at lateral boundary and grows stronger as bacterial density increases. We demonstrate that chiral edge current favors co-rotational configurations of interacting vortices, enhancing their ordering. The interplay between the intrinsic chirality of bacteria and the geometric properties of the boundary is a key-feature for the pairing order transition of active turbulence.
@article{arxiv.2002.01247,
title = {Edge Current and Pairing Order Transition in Chiral Bacterial Vortex},
author = {Kazusa Beppu and Ziane Izri and Tasuku Sato and Yoko Yamanishi and Yutaka Sumino and Yusuke T. Maeda},
journal= {arXiv preprint arXiv:2002.01247},
year = {2021}
}