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abstract: '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.'
author:
- Kazusa Beppu
- Ziane Izri
- Tasuku Sato
- Yoko Yamanishi
- Yutaka Sumino
- 'Yusuke T. Maeda'
- Kazusa Beppu
- Ziane Izri
- Tasuku Sato
- Yoko Yamanishi
- Yutaka Sumino
- 'Yusuke T. Maeda'
title: Edge Current and Pairing Order Transition in Chiral Bacterial Vortex
---

Turbulent flows offer a rich variety of structures at large length scales and are usually obtained by driving flows out of equilibrium[@zhang] while overcoming viscous dampening. A peculiar class of out-of-equilibrium fluids, stimulated from the lower scales, also present turbulence-like structures called active turbulence [@ramaswamy; @marchetti]. For 