Flocking at a distance in active granular matter

Abstract

The self-organised motion of vast numbers of creatures in a single direction is a spectacular example of emergent order. We recreate this phenomenon using actuated non-living components. We report here that millimetre-sized tapered rods, rendered motile by contact with an underlying vibrated surface and interacting through a medium of spherical beads, undergo a phase transition to a state of spontaneous alignment of velocities and orientations above a threshold bead area fraction. Guided by a detailed simulation model, we construct an analytical theory of this flocking transition, with two ingredients: a moving rod drags beads; neighbouring rods reorient in the resulting flow like a weathercock in the wind. Theory and experiment agree on the structure of our phase diagram in the plane of rod and bead concentrations and power-law spatial correlations near the phase boundary. Our discovery suggests possible new mechanisms for the collective transport of particulate or cellular matter.

32 pages, 14 figures, Supplementary Videos: http://www.tifrh.res.in/tcis/events/sriram_videos/

References in corpus (6)

• Emergence of macroscopic directed motion in populations of motile colloids
• Propulsion of a molecular machine by asymmetric distribution of reaction--products
• Diffusive transport without detailed balance in motile bacteria: Does microbiology need statistical physics?
• Swarming and swirling in self-propelled polar granular rods
• Living clusters and crystals from low density suspensions of active colloids
• Symmetry properties of the large-deviation function of the velocity of a self-propelled polar particle

Cited by in corpus (156)

• Active Particles in Complex and Crowded Environments
• Physical Models of Collective Cell Migration
• Topological active matter
• Active matter
• Emergent vortices in populations of colloidal rollers
• The statistical physics of active matter: from self-catalytic colloids to living cells
• Directed collective motion of bacteria under channel confinement
• Stabilization of active matter by flow-vortex lattices and defect ordering
• Tunable structure and dynamics of active liquid crystals
• Dense active matter model of motion patterns in confluent cell monolayers
• Data-driven quantitative modeling of bacterial active nematics
• Long-range nematic order and anomalous fluctuations in suspensions of swimming filamentous bacteria
• Mesoscopic Turbulence and Local Order in Janus Particles Self-Propelling under an AC Electric Field
• Structuring Stress for Active Materials Control
• Active Brownian Motion in Two Dimensions
• Verticalization of bacterial biofilms
• Collective Motion of Self-Propelled Particles with Memory
• Steady State of an Active Brownian Particle in Two-Dimensional Harmonic Trap
• A classical nucleation theory description of active colloid assembly
• Run-and-tumble particles in two-dimensions : Marginal position distributions
• Activity controls fragility: A Random First Order Transition Theory for an active glass
• Sounds and hydrodynamics of polar active fluids
• Freezing a Flock: Motility-Induced Phase Separation in Polar Active Liquids
• Generic long-range interactions between passive bodies in an active fluid
• Insensitivity of active nematic dynamics to topological constraints
• Exact stationary state of a run-and-tumble particle with three internal states in a harmonic trap
• Long time position distribution of an active Brownian particle in two dimensions
• Nonmutual torques and the unimportance of motility for long-range order in two-dimensional flocks
• Run-and-Tumble particles in Two-dimensions under Stochastic Resetting
• Asymmetric exchange in flocks
• Flocking without alignment interactions in attractive active Brownian particles
• Origins and diagnostics of the nonequilibrium character of active systems
• Active Brownian Motion in two-dimensions under Stochastic Resetting
• Nonequilibrium mode-coupling theory for dense active systems of self-propelled particles
• Robust boundary flow in chiral active fluid
• Trapping and sorting active particles: motility-induced condensation & smectic defects
• Sorting motile rods by activity
• Schools of skyrmions with electrically tunable elastic interactions
• Topological defects in solids with odd elasticity
• The convex hull of the run-and-tumble particle in a plane
• Collective Motion with Anticipation: Flocking, Spinning, and Swarming
• Emergence of dynamic vortex glasses in disordered polar active fluids
• Active nonreciprocal attraction between motile particles in an elastic medium
• Oriented Active Solids
• Comparison between Smoluchowski and Boltzmann approaches for self-propelled rods
• Active dumbbells: dynamics and morphology in the coexisting region
• Susceptibility of Polar Flocks to Spatial Anisotropy
• Elasticity Induced Force Reversal Between Active Spinning Particles in Dense Passive Media
• Collective motion in large deviations of active particles
• Universal scaling in active single-file dynamics
• Phase segregation of passive advective particles in an active medium
• Collective Directional Locking of Colloidal Monolayers on a Periodic Substrate
• Active Matter Class with Second-Order Transition to Quasi-Long-Range Polar Order
• Active Brownian and inertial particles in disordered environments: short-time expansion of the mean-square displacement
• Spontaneous rotation can stabilise ordered chiral active fluids
• Swimmer suspensions on substrates: anomalous stability and long-range order
• Chiral Active Particles are Sensitive Reporter to Environmental Geometry
• Glassy swirls of active dumbbells
• Ordering in granular rod monolayers driven far from thermodynamic equilibrium
• Crowding-Enhanced Diffusion: An Exact Theory for Highly Entangled Self-Propelled Stiff Filaments
• Collective behavior of strongly confined suspensions of squirmers
• Time-reversal symmetry violations and entropy production in field theories of polar active matter
• Small Obstacle in a Large Polar Flock
• Mean area of the convex hull of a run and tumble particle in two dimensions
• Anisotropic Isometric Fluctuation Relations in experiment and theory on a self-propelled rod
• Exact position distribution of a harmonically-confined run-and-tumble particle in two dimensions
• Topology-driven ordering of flocking matter
• Heterogeneous bacterial swarms with mixed lengths
• Approach to equilibrium and non-equilibrium stationary distributions of interacting many-particle systems that are coupled to different heat baths
• Transient Casimir forces from quenches in thermal and active matter
• Blood crystal: emergent order of red blood cells under wall-confined shear flow
• Bodies in an Interacting Active Fluid: Far-Field Influence of a Single Body and Interaction Between Two Bodies
• Activity-driven phase transition causes coherent flows of chromatin
• Heat fluctuations in a harmonic chain of active particles
• Inertial active matter with Coulomb friction
• Non-equilibrium forces following quenches in active and thermal matter
• Fluctuating hydrodynamics and mesoscopic effects of spatial correlations in dissipative systems with conserved momentum
• Optically enriched and guided dynamics of active skyrmions
• Programming tunable active dynamics in a self-propelled robot
• The escape problem for active particles confined to a disc
• Coherent motion of monolayer sheets under confinement and its pathological implications
• Coarsening in the two-dimensional incompressible Toner-Tu equation: Signatures of turbulence
• Exact moments and re-entrant transitions in the inertial dynamics of active Brownian particles
• Intermittent relaxation and avalanches in extremely persistent active matter
• Motile topological defects hinder dynamical arrest in dense liquids of active ellipsoids
• Interface height fluctuations and surface tension of driven liquids with time-dependent dynamics
• Hohenberg-Mermin-Wagner type theorems for equilibrium models of flocking
• Lattice models for granular-like velocity fields: Hydrodynamic limit
• Packed swarms on dirt: two-dimensional incompressible flocks with quenched and annealed disorder
• Universal properties of repulsive self-propelled particles and attractive driven particles
• Wildebeest Herds on Rolling Hills: Flocking on Arbitrary Curved Surfaces
• Motile dissenters disrupt the flocking of active granular matter
• Polar active liquids: a universal classification rooted in nonconservation of momentum
• Topological sound in active-liquid metamaterials
• Roadmap for Animate Matter
• Nonequilibrium steady state of trapped active particles
• Inter-particle adhesion regulates the surface roughness of growing dense three-dimensional active particle aggregates
• Emergence of bidirectional cell laning from collective contact guidance
• Three-body problem for Langevin dynamics with different temperatures
• Shear Induced Orientational Ordering in Active Glass
• Dynamics of switching processes: general results and applications to intermittent active motion
• Flocking in One Dimension: Asters and Reversals
• Enhanced orientational ordering induced by active yet isotropic bath
• Experimental observation of gapped shear waves and liquid-like to gas-like dynamical crossover in active granular matter
• Controlling the transport of active matter in disorderd lattices of asymmetrical obstacles
• Catapulting of topological defects through elasticity bands in active nematics
• Energetics of critical oscillators in active bacterial baths
• Flocking of Active Particles in a Turbulent Flow
• Coupling spin to velocity: collective motion of Hamiltonian polar particles
• Confined run and tumble particles with non-Markovian tumbling statistics
• Order-disorder transition in active nematic: A lattice model study
• Pushing run-and-tumble particles through a rugged channel
• Deriving hydrodynamic equations from dry active matter models in three dimensions
• Bulk condensation by an active interface
• Active uniaxially ordered suspensions on disordered substrates
• From predicting to learning dissipation from pair correlations of active liquids
• Active particle in a harmonic trap driven by a resetting noise: an approach via Kesten variables
• Motility-Induced Pinning in Flocking System with Discrete Symmetry
• Stability of flocking in the reciprocal two-species Vicsek model: Effects of relative population, motility, and noise
• A mean-field model for nematic alignment of self-propelled rods
• Boundaries control active channel flows
• From Flocking to Condensation: Collective Dynamics in Binary Chiral Active Matter
• Phases and correlations in active nematic granular systems
• Disentangling intrinsic motion from neighbourhood effects in heterogeneous collective motion
• Spatio-temporal correlations in Wigner molecules
• Cluster dynamics in macroscopic photoactive particles
• Mean-field theory for the structure of strongly interacting active liquids
• Gaussian theory for spatially distributed self-propelled particles
• Micellization in active matter of asymmetric self-propelled particles: Experiments
• Reentrant phase behavior in binary topological flocks with nonreciprocal alignment
• Self-Aligning Active Agents with Inertia and Active Torque
• Siegmund duality for physicists: a bridge between spatial and first-passage properties of continuous and discrete time stochastic processes
• Collective Motion in Active Materials: Model Experiments
• Quadrupolar active stress induces exotic phases of defect motion in active nematics
• Topological signatures of collective dynamics and turbulent-like energy cascades in apolar active granular
• Moving efficiently through a crowd: a nature inspired traffic rule
• Hermitian and non-Hermitian topology in active matter
• Ballistic propagation of density correlations and excess wall forces in quenched granular media
• Temperature overshooting in the Mpemba effect of frictional active matter
• Dynamic Phases and Combing Effects for Elongated Particles Moving Over Quenched Disorder
• Two-Dimensional Active Brownian Particles Crossing a Parabolic Barrier: Transition-Path Times, Survival Probability, and First-Passage Time
• Active osmotic-like pressure on permeable inclusions
• Properties of the dissipation functions for passive and active systems
• Bubble formation in active binary mixture model
• Memory effects, arches and polar defect ordering at the cross-over from wet to dry active nematics
• Inertia-chirality interplay in active Brownian motion: exact dynamics and phase maps
• Universal framework for the long-time position distribution of free active particles
• When soft crystals defy Newton's third law: Non-reciprocal mechanics and dislocation motility
• Active Caustics
• Boundary layers, transport and universal distribution in boundary driven active systems
• Collective behaviors of self-propelled particles with tunable alignment angles
• Pseudo-giant number fluctuations and nematic order in microswimmer suspensions
• Hydrodynamic bend instability of motile particles on a substrate
• Imaging the emergence of bacterial turbulence: phase diagram and transition kinetics
• Edge states, pairing, and sorting of motile chiral particles
• Collective dynamics of macroscopic photoactive matter under alternating excitation patterns