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Main Authors: Kant, Raushan, Maitra, Ananyo, Sood, A K, Ramaswamy, Sriram
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2509.00729
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author Kant, Raushan
Maitra, Ananyo
Sood, A K
Ramaswamy, Sriram
author_facet Kant, Raushan
Maitra, Ananyo
Sood, A K
Ramaswamy, Sriram
contents We present experiments on chiral active polar particles, realized as vibrated granular rods, revealing the formation of robust ``skipping orbits'' at hard boundaries. These 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.
format Preprint
id arxiv_https___arxiv_org_abs_2509_00729
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Edge states, pairing, and sorting of motile chiral particles
Kant, Raushan
Maitra, Ananyo
Sood, A K
Ramaswamy, Sriram
Soft Condensed Matter
We present experiments on chiral active polar particles, realized as vibrated granular rods, revealing the formation of robust ``skipping orbits'' at hard boundaries. These 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.
title Edge states, pairing, and sorting of motile chiral particles
topic Soft Condensed Matter
url https://arxiv.org/abs/2509.00729