Scalar Active Mixtures: The Nonreciprocal Cahn-Hilliard Model

Saha, Suropriya; Agudo-Canalejo, Jaime; Golestanian, Ramin

doi:10.1103/physrevx.10.041009

Cited by 143 publications

(103 citation statements)

References 64 publications

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“…1A corresponds to a so-called "exceptional point" where the eigenmodes of the matrix controlling the dynamical stability of the system coalesce (42)(43)(44). In parallel to our investigation, Saha et al (45) have also reported traveling density waves in scalar fields with Cahn-Hilliard dynamics and nonreciprocal couplings. The simulations carried out by these authors support our finding that nonreciprocal couplings provide a generic mechanism for breaking time-reversal symmetry and setting spatial patterns in motion.…”

Section: Significancesupporting

confidence: 83%

Nonreciprocity as a generic route to traveling states

You

Baskaran

Marchetti

2020

Proc. Natl. Acad. Sci. U.S.A.

132

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We examine a nonreciprocally coupled dynamical model of a mixture of two diffusing species. We demonstrate that nonreciprocity, which is encoded in the model via antagonistic cross-diffusivities, provides a generic mechanism for the emergence of traveling patterns in purely diffusive systems with conservative dynamics. In the absence of nonreciprocity, the binary fluid mixture undergoes a phase transition from a homogeneous mixed state to a demixed state with spatially separated regions rich in one of the two components. Above a critical value of the parameter tuning nonreciprocity, the static demixed pattern acquires a finite velocity, resulting in a state that breaks both spatial and time-reversal symmetry, as well as the reflection parity of the static pattern. We elucidate the generic nature of the transition to traveling patterns using a minimal model that can be studied analytically. Our work has direct relevance to nonequilibrium assembly in mixtures of chemically interacting colloids that are known to exhibit nonreciprocal effective interactions, as well as to mixtures of active and passive agents where traveling states of the type predicted here have been observed in simulations. It also provides insight on transitions to traveling and oscillatory states seen in a broad range of nonreciprocal systems with nonconservative dynamics, from reaction–diffusion and prey–predators models to multispecies mixtures of microorganisms with antagonistic interactions.

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Section: Significancesupporting

confidence: 83%

Nonreciprocity as a generic route to traveling states

You

Baskaran

Marchetti

2020

Proc. Natl. Acad. Sci. U.S.A.

132

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“…Chirality has been shown to be important in epithelial cell layers [30] and a density modulated phase in these systems will lead to another realisation of two dimensional cholesterics. Non-mutual, two-species Cahn-Hilliard models [68,69] also spontaneously form banded phases and chiral variants of these models would lead to two-dimensional chiral layered states. Finally, two-dimensional smectic phases in parity-broken systems are also possible in twodimensional electron gases [70] and, when they are irradiated by microwave radiation [71], may have a dynamics equivalent to the one described here.…”

mentioning

confidence: 99%

Layered Chiral Active Matter: Beyond Odd Elasticity

Alexander²,

Ramaswamy³

et al. 2021

Phys. Rev. Lett.

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“…1c). This non-reciprocity, characteristic of active matter systems [12][13][14][15][29][30][31][32], can give rise to interesting many-body phenomena, which we will study here.…”

Section: Model For Chemically Active Particlesmentioning

confidence: 99%

Non-equilibrium phase separation in mixtures of catalytically active particles: size dispersity and screening effects

2021

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Biomolecular condensates in cells are often rich in catalytically active enzymes. This is particularly true in the case of the large enzymatic complexes known as metabolons, which contain different enzymes that participate in the same catalytic pathway. One possible explanation for this self-organization is the combination of the catalytic activity of the enzymes and a chemotactic response to gradients of their substrate, which leads to a substrate-mediated effective interaction between enzymes. These interactions constitute a purely non-equilibrium effect and show exotic features such as non-reciprocity. Here, we analytically study a model describing the phase separation of a mixture of such catalytically active particles. We show that a Michaelis–Menten-like dependence of the particles’ activities manifests itself as a screening of the interactions, and that a mixture of two differently sized active species can exhibit phase separation with transient oscillations. We also derive a rich stability phase diagram for a mixture of two species with both concentration-dependent activity and size dispersity. This work highlights the variety of possible phase separation behaviours in mixtures of chemically active particles, which provides an alternative pathway to the passive interactions more commonly associated with phase separation in cells. Our results highlight non-equilibrium organizing principles that can be important for biologically relevant liquid-liquid phase separation. Graphic abstract

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Scalar Active Mixtures: The Nonreciprocal Cahn-Hilliard Model

Cited by 143 publications

References 64 publications

Nonreciprocity as a generic route to traveling states

Nonreciprocity as a generic route to traveling states

Layered Chiral Active Matter: Beyond Odd Elasticity

Non-equilibrium phase separation in mixtures of catalytically active particles: size dispersity and screening effects

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