Flocking at a distance in active granular matter

The self-organized motion of vast numbers of creatures in a single direction is a spectacular example of emergent order. Here, we recreate this phenomenon using actuated nonliving 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. Flocking emerges from communication within groups of animals. Here, Kumar et al. create a flock in inanimate matter, by showing that a vibrated layer of a small number of millimetre-sized tapered rods, amidst a background of spherical beads, spontaneously aligns into a state of coherent motion.

• Publication year

  2014

• Venue

  Nature Communications

• Publication date

  2014-02-18

• Fields of study

  Materials Science, Physics, Medicine

• Identifiers
  DOI 10.1038/ncomms5688arXiv 1402.4262PMID 25181961
• External record

  Open on Semantic Scholar

• Source metadata

  Semantic Scholar, PubMed

• No claims are published for this paper.

• No concepts are published for this paper.

• Bird Flocks as Condensed Matter

  2014cited by this paper
• Emergence of macroscopic directed motion in populations of motile colloids

  2013influential reference
• Living Crystals of Light-Activated Colloidal Surfers

  2013cited by this paper
• Living clusters and crystals from low-density suspensions of active colloids.

  2013cited by this paper
• Hydrodynamics of soft active matter

  2013cited by this paper
• Clusters, asters, and collective oscillations in chemotactic colloids.

  2013cited by this paper
• Hydrodynamics of confined active fluids.

  2012cited by this paper
• Athermal phase separation of self-propelled particles with no alignment.

  2012cited by this paper
• Diffusive transport without detailed balance in motile bacteria: does microbiology need statistical physics?

  2012cited by this paper
• Collective motion of vibrated polar disks.

  2010cited by this paper
• Polar patterns of driven filaments

  2010cited by this paper
• Symmetry properties of the large-deviation function of the velocity of a self-propelled polar particle.

  2010cited by this paper
• The Mechanics and Statistics of Active Matter

  2010cited by this paper
• Phase Behaviour & Dynamics Of An Agitated Monolayer Of Granular Rods

  2008cited by this paper
• Active elastic dimers: self-propulsion and current reversal on a featureless track.

  2007cited by this paper
• Swarming and swirling in self-propelled polar granular rods.

  2007cited by this paper
• Model for dynamical coherence in thin films of self-propelled microorganisms.

  2007cited by this paper
• Long-Lived Giant Number Fluctuations in a Swarming Granular Nematic

  2006cited by this paper
• From Disorder to Order in Marching Locusts

  2006cited by this paper
• Boltzmann and hydrodynamic description for self-propelled particles.

  2006cited by this paper
• Hydrodynamics of polar liquid crystals.

  2005cited by this paper
• Hydrodynamics and phases of flocks

  2005cited by this paper
• Propulsion of a molecular machine by asymmetric distribution of reaction products.

  2005cited by this paper
• Onset of collective and cohesive motion.

  2004cited by this paper
• Catalytic nanomotors: autonomous movement of striped nanorods.

  2004cited by this paper
• Coherent dynamics of an asymmetric particle in a vertically vibrating bed.

  2003cited by this paper
• Self-organized lane formation and optimized traffic flow in army ants

  2003cited by this paper
• Collective Motion

  1999cited by this paper
• Flocks, herds, and schools: A quantitative theory of flocking

  1998influential reference
• Modeling molecular motors

  1997cited by this paper
• Impulse-based dynamic simulation of rigid body systems

  1996cited by this paper
• The Dynamics of Herds: From Individuals to Aggregations

  1996cited by this paper
• VMD: visual molecular dynamics.

  1996cited by this paper
• Swerve During Three-Dimensional Impact of Rough Rigid Bodies

  1994cited by this paper
• Linear and nonlinear hydrodynamics of low-friction adsorbed systems

  1982cited by this paper
• Unified Hydrodynamic Theory for Crystals, Liquid Crystals, and Normal Fluids

  1972cited by this paper

• Spectral Insights into Active Matter: Exceptional Points and the Mathieu Equation

  2026cites this paper
• Exact Stationary State of a $d$-dimensional Run-and-Tumble Particle in a Harmonic Potential

  2026cites this paper
• Breakdown and Restoration of Hydrodynamics in Dipole-conserving Active Fluids

  2026cites this paper
• Topological signatures of collective dynamics and turbulent-like energy cascades in apolar active granular matter.

  2025cites this paper
• Collective behaviors of self-propelled particles with tunable alignment angles.

  2025cites this paper
• Emergence of collective oscillations in massive human crowds

  2025cites this paper
• Self-sustained frictional cooling in active matter

  2025cites this paper
• Toothpicks and toy football players: frictional jamming causes locomotion of vertically-shaken assymetrical objects.

  2025cites this paper
• Depletion effect in an active chiral system.

  2025cites this paper
• Thermodynamically consistent lattice Monte Carlo method for active particles

  2025cites this paper
• Cooling mechanism controls motility-induced phase separation in inertial active liquids

  2025cites this paper
• Anisotropic active Brownian particle in two dimensions under stochastic resetting.

  2025cites this paper
• Edge states, pairing, and sorting of motile chiral particles

  2025influential citation
• Statistical mechanics of an active wheel rolling in circles.

  2025cites this paper
• Bubble formation in active binary mixture model

  2025cites this paper
• Active-noise-induced dynamic clustering of passive colloidal particles

  2025cites this paper
• Active particles in power-law potentials: steady state distributions and shape transitions

  2025cites this paper
• Transition path dynamics for one-dimensional run and tumble particle.

  2025cites this paper
• Moment analysis of two-dimensional active Brownian run-and-tumble particles.

  2025cites this paper
• Pseudogiant Number Fluctuations and Nematic Order in Microswimmer Suspensions.

  2025cites this paper
• Motor-driven microtubule diffusion in a photobleached dynamical coordinate system

  2025cites this paper
• Activated solids: Spontaneous deformations, non-affine fluctuations, softening, and failure

  2025cites this paper
• Hydrodynamic Bend Instability of Motile Particles on a Substrate.

  2025cites this paper
• A motile rod in an active nematic medium: caging, orientational trapping, and anomalous diffusion.

  2025cites this paper
• Two-dimensional active Brownian particles crossing a parabolic barrier: Transition-path times, survival probability, and first-passage time.

  2025cites this paper
• Stability of flocking in the reciprocal two-species Vicsek model: Effects of relative population, motility, and noise.

  2025cites this paper
• Self-alignment and anti-self-alignment suppress motility-induced phase separation in active systems.

  2025cites this paper
• Maneuvering superparamagnetic particles in a nematic liquid crystal by transverse electric and in-plane rotating magnetic fields

  2024cites this paper
• Rocking, Rolling, and Hopping: Exploring the Multi-motion Capabilities of Rigid and Soft Ellipsoidal Actuators

  2024cites this paper
• Dynamics of switching processes: general results and applications in intermittent active motion.

  2024cites this paper
• Exact moments for a run-and-tumble particle with a finite tumble time in a harmonic trap.

  2024cites this paper
• Ordering spontaneous flows and aging in active fluids depositing tracks.

  2024cites this paper
• From flocking to condensation: Collective dynamics in binary chiral active matter

  2024cites this paper
• Anomalous Long-Ranged Influence of an Inclusion in Momentum-Conserving Active Fluids

  2024cites this paper
• Hermitian and non-Hermitian topology in active matter

  2024cites this paper
• Motor-driven microtubule diffusion in a photobleached dynamical coordinate system

  2024cites this paper
• Anomalous flocking in nonpolar granular Brownian vibrators

  2024cites this paper
• A perspective on active glassy dynamics in biological systems

  2024cites this paper
• Stochastic migrations of Marangoni surfers between two lobes of a dumbbell-shaped confinement.

  2024cites this paper
• Bulk Condensation by an Active Interface.

  2024influential citation
• Inertial active Ornstein–Uhlenbeck particle in a non-linear velocity dependent friction

  2024cites this paper
• Exact moments for trapped active particles: inertial impact on steady-state properties and re-entrance

  2024cites this paper
• Diffusion of active Brownian particles under quenched disorder

  2024cites this paper
• Siegmund duality for physicists: a bridge between spatial and first-passage properties of continuous- and discrete-time stochastic processes

  2024cites this paper
• Dynamics of self-propelled particles in vibrated dense granular media.

  2024cites this paper
• Dynamical clustering and wetting phenomena in inertial active matter

  2024cites this paper
• Experimental observation of gapped shear waves and liquid-like to gas-like dynamical crossover in active granular matter

  2024cites this paper
• Roadmap for animate matter

  2024cites this paper
• Inertial Active Matter with Coulomb Friction.

  2024cites this paper
• Spontaneous unidirectional rotation of a symmetric gear driven by spherical active particles

  2024cites this paper
• Spontaneous generation of angular momentum in chiral active crystals.

  2024cites this paper
• Phases and correlations in active nematic granular systems.

  2024cites this paper
• Boundary layers, transport and universal distribution in boundary driven active systems

  2024cites this paper
• A shape-driven reentrant jamming transition in confluent monolayers of synthetic cell-mimics

  2024cites this paper
• Self-aligning active agents with inertia and active torque.

  2024cites this paper
• Cluster Dynamics in Macroscopic Photoactive Particles.

  2024cites this paper
• Confined run-and-tumble particles with non-Markovian tumbling statistics.

  2024cites this paper
• Can flocking aid the path planning of microswimmers in turbulent flows?

  2024cites this paper
• Active many-particle systems and the emergent behavior of dense ant collectives

  2024cites this paper
• The Anomalous Long-Ranged Influence of an Inclusion in Momentum-Conserving Active Fluids

  2024cites this paper
• Emergence of bidirectional cell laning from collective contact guidance

  2024cites this paper
• Spontaneous self-wrapping in chiral active polymers

  2024cites this paper
• Reentrant phase behavior in binary topological flocks with nonreciprocal alignment

  2024cites this paper
• Motility-Induced Pinning in Flocking System with Discrete Symmetry.

  2024cites this paper
• Programming tunable active dynamics in a self-propelled robot

  2023cites this paper
• Active particle in a harmonic trap driven by a resetting noise: an approach via Kesten variables

  2023cites this paper
• Deciphering Long-Range Order in Active Matter: Insights from Swimming Bacteria in Quasi-2D and Electrokinetic Janus Particles

  2023cites this paper
• Micellization in active matter of asymmetric self-propelled particles: Experiments.

  2023cites this paper
• Universal properties of repulsive self-propelled particles and attractive driven particles

  2023cites this paper
• Activity-Driven Phase Transition Causes Coherent Flows of Chromatin.

  2023cites this paper
• Nonequilibrium steady state of trapped active particles.

  2023cites this paper
• Long-range velocity correlations from active dopants

  2023cites this paper
• The narrow escape problem of a chiral active particle (CAP): an optimal scheme.

  2023cites this paper
• Spatial confinement affects the heterogeneity and interactions between shoaling fish

  2023cites this paper
• Emergent memory from tapping collisions in active granular matter

  2023cites this paper
• Three-dimensional spontaneous flow transition in a homeotropic active nematic

  2023cites this paper
• Exact moments and re-entrant transitions in the inertial dynamics of active Brownian particles

  2023cites this paper
• Dynamic phases and combing effects for elongated particles moving over quenched disorder.

  2023cites this paper
• Anomalous large-scale collective motion in granular Brownian vibrators

  2023cites this paper
• Chiral active particles are sensitive reporters to environmental geometry

  2023cites this paper
• Entropy production and collective excitations of crystals out of equilibrium: The concept of entropons.

  2023cites this paper
• Nonequilibrium phase transitions in a Brownian p-state clock model.

  2023cites this paper
• Flocking without Alignment Interactions in Attractive Active Brownian Particles.

  2023cites this paper
• Motile Topological Defects Hinder Dynamical Arrest in Dense Liquids of Active Ellipsoids.

  2022cites this paper
• Catapulting of topological defects through elasticity bands in active nematics.

  2022cites this paper
• Activity mediated globule to coil transition of a flexible polymer in a poor solvent.

  2022cites this paper
• Migration of an active colloidal cell in inhomogeneous environments.

  2022cites this paper
• Intermittent relaxation and avalanches in extremely persistent active matter.

  2022cites this paper
• On a numerical bifurcation analysis of a particle reaction-diffusion model for a motion of two self-propelled disks

  2022cites this paper
• Susceptibility of Polar Flocks to Spatial Anisotropy.

  2022cites this paper
• Reentrant phase separation of a sparse collection of nonreciprocally aligning self-propelled disks.

  2022cites this paper
• Properties of the dissipation functions for passive and active systems.

  2022cites this paper
• Chiral nonreciprocal elasticity and mechanical activity

  2022cites this paper
• Collective Motion in Active Materials: Model Experiments

  2022cites this paper
• Active osmoticlike pressure on permeable inclusions.

  2022cites this paper
• Flocking in one dimension: Asters and reversals.

  2022cites this paper
• Experimental investigation of active noise on a rotor in an active granular bath.

  2022cites this paper
• Motor guidance by long-range communication on the microtubule highway

  2022cites this paper
• Symmetry-breaking transition between defect-free and defect-laden turbulence in polar active matter

  2022cites this paper
• Exact position distribution of a harmonically confined run-and-tumble particle in two dimensions.

  2022cites this paper