Edge states, pairing, and sorting of motile chiral particles

Abstract

We present experiments on chiral active polar particles, realised as vibrated granular rods, revealing evidence for ``skipping orbits'' at hard boundaries. These classical edge states exhibit a net circulation opposite to the particles' intrinsic rotation and lead to a pronounced accumulation at the boundary, stronger than for their achiral counterparts. The directed nature of these orbits provides a simple yet high-fidelity mechanism for chiral sorting -- even for solitary particles, unlike in T. Barois et al., Phys. Rev. Lett. 125, 238003 (2020). We propose a unified theoretical framework for boundary interactions of both chiral and achiral particles. In this model, an effective outward radial force, proportional to motility and chirality, explains the observed boundary-hugging. Our theory predicts, and our experiments confirm, a transition in the pairing of two particles of the same chirality, from apolar spinners to polar circle walkers, with increasing packing fraction of an ambient medium of beads.

arXiv commentAdditional relevant references and a subsequent revision of the text were added. For supplementary videos, please click on the link below: https://drive.google.com/drive/folders/1PuTIQuzqR6u_lIjDYuCP-1E8b-gvkZzY. For additional data, please see https://doi.org/10.5281/zenodo.21815017

References in corpus (29)

• Active Particles in Complex and Crowded Environments
• The Mechanics and Statistics of Active Matter
• Swimming in circles: Motion of bacteria near solid boundaries
• Long-lived Giant Number Fluctuations in a Swarming Granular Nematic
• Circular motion of asymmetric self-propelling particles
• Molecular Chirality and Chiral Parameters
• Flocking at a distance in active granular matter
• Odd dynamics of living chiral crystals
• Aggregation of self-propelled colloidal rods near confining walls
• Sorting of Chiral Microswimmers
• Spatiotemporal order and emergent edge currents in active spinner materials
• Hydrodynamics of confined active fluids
• Dynamics of a bouncing dimer
• Origins and diagnostics of the nonequilibrium character of active systems
• Cooperative Self-Propulsion of Active and Passive Rotors
• Reconfigurable Artificial Microswimmers with Internal Feedback
• Self-Aligning Polar Active Matter
• Active Brownian particles near straight or curved walls: Pressure and boundary layers
• Active nonreciprocal attraction between motile particles in an elastic medium
• Emergence of Nonwhite Noise in Langevin Dynamics with Magnetic Lorentz Force
• Swimmer suspensions on substrates: anomalous stability and long-range order
• Statistical Mechanics of Splay Flexoelectricity in Nematic Liquid Crystals
• Chiral Active Particles are Sensitive Reporter to Environmental Geometry
• Oscillatory force autocorrelations in equilibrium odd-diffusive systems
• Chiral active hexatics: Giant number fluctuations, waves and destruction of order
• The Dance of Odd-Diffusive Particles: A Fourier Approach
• Bulk condensation by an active interface
• Reversal of tracer advection and Hall drift in an interacting chiral fluid
• Active screws: Emergent active chiral nematics of spinning self-propelled rods