Synchronization and pattern formation in chiral active matter

The emergence of synchronized states in populations of mobile entities is widely observed in different contexts: from animal groups - like flocks of birds moving coherently or crowds of people walking cooperatively on the London's Millenium bridge - to synthetic colloidal systems. However, previous studies on synchronization have focused on, either immobile oscillators, or mobile oscillators which phase does not directly influence the way they move in space [1]. Here we focus on active oscillators - circle swimmers which rotate with an intrinsic frequency - and show that self-propulsion, induces a qualitatively new and generic synchronization scenario which generates two novel phases: (i) a phase where oscillators move collectively along a given direction; a phase showing long-range order in 2D (akin to the celebrated Toner-Tu flocking phase [2]). (ii) a second phase where particles of opposite chirality segregate into rotating clusters. Both phases feature activity-induced synchronization in 2D, which is not achievable for immobile oscillators in low dimensional systems [3].
[1] D Levis, I Pagonabarraga, A Díaz-Guilera, Phys. Rev. X 7 , 011028, 2017.
[2] J Toner and Y Tu, Phys. Rev. Lett. 75, 4326, 1995.
[3] D Levis, I Pagonabarraga, B Liebchen, arXiv:1802.02371, 2018.