From Phase to Micro-Phase Separation in Flocking Models: The Essential Role of Non-Equilibrium Fluctuations

Abstract

We show that the flocking transition in the Vicsek model is best understood as a liquid-gas transition, rather than an order-disorder one. The full phase separation observed in flocking models with Z2 rotational symmetry is, however, replaced by a microphase separation leading to a smectic arrangement of traveling ordered bands. Remarkably, continuous deterministic descriptions do not account for this difference, which is only recovered at the fluctuating hydrodynamics level. Scalar and vectorial order parameters indeed produce different types of number fluctuations, which we show to be essential in selecting the inhomogeneous patterns. This highlights an unexpected role of fluctuations in the selection of flock shapes.

5 p., 5 fig.. Supplementary material: 7 movies

References in corpus (25)

• Novel type of phase transition in a system of self-driven particles
• Collective motion
• Interaction Ruling Animal Collective Behaviour Depends on Topological rather than Metric Distance: Evidence from a Field Study
• Flocks, herds, and schools: A quantitative theory of flocking
• Spontaneous motion in hierarchically assembled active matter
• Athermal Phase Separation of Self-Propelled Particles with no Alignment
• Emergence of macroscopic directed motion in populations of motile colloids
• Onset of collective and cohesive motion
• Statistical Mechanics of Interacting Run-and-Tumble Bacteria
• Collective motion of self-propelled particles interacting without cohesion
• Collective Motion of Vibrated Polar Disks
• Living Liquid Crystals
• Boltzmann and hydrodynamic description for self-propelled particles
• Collective motion and nonequilibrium cluster formation in colonies of gliding bacteria
• Hydrodynamic equations for self-propelled particles: microscopic derivation and stability analysis
• Pattern formation in self-propelled particles with density-dependent motility
• Fluctuations and Pattern Formation in Self-Propelled Particles
• Revisiting the flocking transition using active spins
• Kinetic Theory of Flocking: Derivation of Hydrodynamic Equations
• A Reanalysis of the Hydrodynamic Theory of Fluid, Polar-Ordered Flocks
• Long-range Ordering of Vibrated Polar Disks
• Boltzmann-Ginzburg-Landau approach for continuous descriptions of generic Vicsek-like models
• Large-scale chaos and fluctuations in active nematics
• Emergent spatial structures in flocking models: a dynamical system insight
• Invasion-wave induced first-order phase transition in systems of active particles

Cited by in corpus (123)

• Active Particles in Complex and Crowded Environments
• How far from equilibrium is active matter?
• Computational models for active matter
• Self-Propelled Rods: Insights and Perspectives for Active Matter
• The statistical physics of active matter: from self-catalytic colloids to living cells
• Spontaneous velocity alignment in Motility-induced Phase Separation
• The Rotating Vicsek Model: Pattern Formation and Enhanced Flocking in Chiral Active Matter
• The Physics of the Vicsek Model
• Entropy production in field theories without time reversal symmetry: Quantifying the non-equilibrium character of active matter
• Distortion and destruction of colloidal flocks in disordered environments
• Long-range nematic order and anomalous fluctuations in suspensions of swimming filamentous bacteria
• Interrupted Motility Induced Phase Separation in Aligning Active Colloids
• Motility-Induced Microphase and Macrophase Separation in a Two-Dimensional Active Brownian Particle System
• Time-(ir)reversibility in active matter: from micro to macro
• Flow-induced phase separation of active particles is controlled by boundary conditions
• Motility-induced phase separation and coarsening in active matter
• Collective Motion of Self-Propelled Particles with Memory
• Exact Hydrodynamic Description of Active Lattice Gases
• Flocking with discrete symmetry: the 2d Active Ising Model
• Optimizing active work: Dynamical phase transitions, collective motion, and jamming
• Freezing a Flock: Motility-Induced Phase Separation in Polar Active Liquids
• Pattern formation in flocking models: A hydrodynamic description
• Optimized Diffusion of Run-and-Tumble Particles in Crowded Environments
• Flocking without alignment interactions in attractive active Brownian particles
• Stationary superstatistics distributions of trapped run-and-tumble particles
• Self-propelled hard disks: implicit alignment and transition to collective motion
• Velocity alignment promotes motility-induced phase separation
• Nonreciprocal pattern formation of conserved fields
• Wavelength selection by interrupted coarsening in reaction-diffusion systems
• How many dissenters does it take to disorder a flock?
• Breakdown of Ergodicity and Self-Averaging in Polar Flocks with Quenched Disorder
• Stealth entropy production in active field theories near Ising critical points
• Fluctuation-induced phase separation in metric and topological models of collective motion
• Dynamical self-assembly of dipolar active Brownian particles in two dimensions
• Active phase separation: new phenomenology from non-equilibrium physics
• Flocking of two unfriendly species: The two-species Vicsek model
• Traveling Bands, Clouds, and Vortices of Chiral Active Matter
• Collective motion in large deviations of active particles
• Susceptibility of Polar Flocks to Spatial Anisotropy
• The low noise phase of a 2d active nematic
• Thermodynamic uncertainty relation for underdamped Langevin systems driven by a velocity-dependent force
• Small noise may diversify collective motion in Vicsek model
• Dry Active Matter exhibits a self-organized 'Cross Sea' Phase
• Interpretable machine learning for inferring the phase boundaries in a nonequilibrium system
• Active Matter Class with Second-Order Transition to Quasi-Long-Range Polar Order
• Collective behavior of self-steering active particles with velocity alignment and visual perception
• Swimmer suspensions on substrates: anomalous stability and long-range order
• Activity-controlled clogging and unclogging of micro-channels
• Time-reversal symmetry violations and entropy production in field theories of polar active matter
• Small Obstacle in a Large Polar Flock
• Emergent smectic order in simple active particle models
• From scalar to polar active matter: Connecting simulations with mean-field theory
• Intermittent Attractive Interactions Lead to Microphase Separation in Non-motile Active Matter
• Fore-aft asymmetric flocking
• Emergence of collective motion in a model of interacting Brownian particles
• Non-reciprocal alignment induces asymmetric clustering in active mixtures
• Designing, Synthesizing and Modeling Active Fluids
• Hydrodynamics of Turning Flocks
• Scale free chaos in the confined Vicsek flocking model
• Flocking and reorientation transition in the 4-state active Potts model
• Contrarian compulsions produce time dependent flocking of active particles
• Diversity of phase transitions and phase separations in active fluids
• Flocking with a $q$-fold discrete symmetry: band-to-lane transition in the active Potts model
• Coarsening and wavelength selection far from equilibrium: a unifying framework based on singular perturbation theory
• Competing Active and Passive Interactions Drive Amoeba-like Living Crystallites and Ordered Bands
• Coarsening Dynamics in the Vicsek Model of Active Matter
• Self-propelled Vicsek particles at low speed and low density
• Helical Flow States in Active Nematics
• Polar active liquids: a universal classification rooted in nonconservation of momentum
• Theoretical approaches to the steady-state statistical physics of interacting dissipative units
• Multiple Particle Correlation Analysis of Many-Particle Systems: Formalism and Application to Active Matter
• Vicsek Model by Time-Interlaced Compression: a Dynamical Computable Information Density
• A Quantitative Kinetic Theory of Flocking with Three-Particle-Closure
• Evidence of fluctuation-induced first-order phase transition in active matter
• Kinetic Monte-Carlo Algorithms for Active-Matter systems
• Dynamical structures in phase-separating non-reciprocal polar active mixtures
• Taming Polar Active Matter with Moving Substrates: Directed Transport and Counterpropagating Macrobands
• Fluctuation-Induced First Order Transition to Collective Motion
• Enhanced orientational ordering induced by active yet isotropic bath
• Flocking in One Dimension: Asters and Reversals
• Nonequilibrium steady states in Langevin thermal systems
• Emergent complex phases in a discrete flocking model with reciprocal and non-reciprocal interactions
• Bose-Einstein-like Condensation due to Diffusivity Edge under Periodic Confinement
• Clustering and anisotropic correlated percolation in polar flocks
• Emergence of a single cluster in Vicsek's model at very low noise
• Minimal stochastic field equations for one-dimensional flocking
• Jamming and flocking in the restricted active Potts model
• The influence of obstacles on collective motion of self-propelled objects
• Novel critical phenomena in compressible polar active fluids: Dynamical and Functional Renormalization Group Studies
• Collective Hall current in chiral active fluids: Coupling of phase and mass transport through traveling bands
• Deriving hydrodynamic equations from dry active matter models in three dimensions
• Crossover between parabolic and hyperbolic scaling, oscillatory modes and resonances near flocking
• Machine learning phases of active matter
• Nematic Torques in Scalar Active Matter: when Fluctuations Favor Polar Order and Persistence
• Microphase separation in active filament systems is maintained by cyclic dynamics of cluster size and order
• Three-body Interactions Drive the Transition to Polar Order in a Simple Flocking Model
• Transport coefficients of self-propelled particles: Reverse perturbations and transverse current correlations
• Motility-Induced Pinning in Flocking System with Discrete Symmetry
• Transport coefficients of self-propelled particles. II. Numerics for vorticity fluctuations and the reverse perturbation method
• Power-law correlation in the homogeneous disordered state of anisotropically self-propelled systems
• Stability of flocking in the reciprocal two-species Vicsek model: Effects of relative population, motility, and noise
• Out of equilibrium stationary states, percolation, and sub-critical instabilities in a fully non conservative system
• Nonquenched rotators ease flocking and memorise it
• Turn towards the crowd
• Adaptive stochastic continuation with a modified lifting procedure applied to complex systems
• Flip motion of solitary wave in an Ising-type Vicsek model
• Ordering kinetics in the active Ising model
• Gaussian theory for spatially distributed self-propelled particles
• Reentrant phase behavior in binary topological flocks with nonreciprocal alignment
• Additivity and density fluctuations in Vicsek-like models of self-propelled particles
• Vicsek Model Meets DBSCAN: Cluster Phases in the Vicsek Model
• Consequence of anisotropy on flocking: the discretized Vicsek model
• Three-state active lattice gas: a discrete Vicseklike model with excluded volume
• Hermitian and non-Hermitian topology in active matter
• Discrete Laplacian thermostat for flocks and swarms: the fully conserved Inertial Spin Model
• Shearing effects on the phase coarsening of binary mixtures using the Active Model B
• Transient phases in the Vicsek model of flocking
• Flocking and spreading dynamics in populations of self-propelled agents
• Sedimentation and structure of squirmer suspensions under gravity
• Stability of discrete-symmetry flocks: sandwich state, traveling domains and motility-induced pinning
• Bubble formation in active binary mixture model
• Morphology, Polarization Patterns, Compression, and Entropy Production in Phase-Separating Active Dumbbell Systems
• Field-controlled interfacial transport and pinning in an active spin system