Hybrid topology guides active matter in a stochastic circuit

Spontaneous behaviour can arise when a collection of active matter entities encounters, such in bird swarming [1]. Recent studies mimic these events in artificial systems to study and achieve a better understanding of new phenomena,[2] posting as one of the main challenges the guidance of large amount of particles without applying an external stimuli (i.e. electromagnetic fields) [3].

In this work we follow an alternative approach to guide these artificial entities, based on the topology. We demonstrate that depending on the internal structure of the device, our artificial entities, the Janus colloids, are topologically driven, leading to an increase in the particle flow. Topologically controlled transport also shows accumulation of active particles on the corners of the device, due to the non-Hermitian skin effect. This work sets a principle to design patterned surfaces that display spontaneous, robust, and predictable guided particle motion, guaranteed by Hermitian and non-Hermitian topology.

[1] Andrea Cavagna et Al., Annual Review of Condensed Matter Physics 5.1 (2014)
[2] Ana C. Hortelao et Al, Submitted and bioRxiv (2020)
[3] Islam S. M. Khalil et Al., International Journal of Advanced Robotic Systems (2015)