Non-Gaussian noise without memory in active matter

Fodor, Étienne; Hayakawa, Hisao; Tailleur, Julien; Wijland, Frédéric van

doi:10.1103/physreve.98.062610

Cited by 25 publications

(21 citation statements)

References 87 publications

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“…As a result, the commonly used active Brownian particle model emerges in a way that allows us to disentangle chemical aspects of entropy production from coarse-grained ones. We thus have formalised the concept of active force [19,20,[87][88][89] and work [70,[83][84][85], previously used in theoretical models, from a thermodynamic perspective. Moreover, we have shown how the work that can be extracted on a macroscopic scale is related to this active work.…”

Section: Discussionmentioning

confidence: 99%

“…that is performed by an effective active force apparently providing propulsion in the direction of n i [70,[83][84][85]. Such an active force is commonly used ad hoc in theoretical models for active particles that discard the details of the self-propulsion mechanism [19,20,[86][87][88][89]. It can be determined phenomenologically as the force required to stall an active particle with persistent director n. Experimentally, the active force can also be measured for a single free active particle that undergoes rotational and translational diffusion.…”

Section: A Setting and Energeticsmentioning

confidence: 99%

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Autonomous Engines Driven by Active Matter: Energetics and Design Principles

et al. 2019

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Because of its nonequilibrium character, active matter in a steady state can drive engines that autonomously deliver work against a constant mechanical force or torque. As a generic model for such an engine, we consider systems that contain one or several active components and a single passive one that is asymmetric in its geometrical shape or its interactions. Generally, one expects that such an asymmetry leads to a persistent, directed current in the passive component, which can be used for the extraction of work. We validate this expectation for a minimal model consisting of an active and a passive particle on a one-dimensional lattice. It leads us to identify thermodynamically consistent measures for the efficiency of the conversion of isotropic activity to directed work. For systems with continuous degrees of freedom, work cannot be extracted using a one-dimensional geometry under quite general conditions. In contrast, we put forward two-dimensional shapes of a movable passive obstacle that are best suited for the extraction of work, which we compare with analytical results for an idealised work-extraction mechanism. For a setting with many noninteracting active particles, we use a mean-field approach to calculate the power and the efficiency, which we validate by simulations. Surprisingly, this approach reveals that the interaction with the passive obstacle can mediate cooperativity between otherwise noninteracting active particles, which enhances the extracted power per active particle significantly. arXiv:1905.00373v2 [cond-mat.stat-mech]

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Section: Discussionmentioning

confidence: 99%

Section: A Setting and Energeticsmentioning

confidence: 99%

Autonomous Engines Driven by Active Matter: Energetics and Design Principles

et al. 2019

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“…Subsequent theoretical calculations for the τ → ∞ limit posited that a departure from equilibrium efficiencies requires noise not just with non-Gaussian statistics but also with memory, a feature typical of active baths due to the persistent motion of the particles 15 . In fact, when the bath noise is non-Gaussian and white, an effective temperature T eff defined through the variance of ρ ( x ) is thought to act like a bona fide temperature 15 , 16 and engines operating between such baths are expected to perform like thermal ones in the quasistatic limit. Whether this similarity persists when τ is reduced and irreversibility begins to set in is not known and is worth exploring since real heat engines never operate in the quasistatic limit as here their power P → 0.…”

Section: Introductionmentioning

confidence: 99%

Tuning the performance of a micrometer-sized Stirling engine through reservoir engineering

et al. 2021

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Colloidal heat engines are paradigmatic models to understand the conversion of heat into work in a noisy environment - a domain where biological and synthetic nano/micro machines function. While the operation of these engines across thermal baths is well-understood, how they function across baths with noise statistics that is non-Gaussian and also lacks memory, the simplest departure from the thermal case, remains unclear. Here we quantified the performance of a colloidal Stirling engine operating between an engineered memoryless non-Gaussian bath and a Gaussian one. In the quasistatic limit, the non-Gaussian engine functioned like a thermal one as predicted by theory. On increasing the operating speed, due to the nature of noise statistics, the onset of irreversibility for the non-Gaussian engine preceded its thermal counterpart and thus shifted the operating speed at which power is maximum. The performance of nano/micro machines can be tuned by altering only the nature of reservoir noise statistics.

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“…Such models violate Einstein's locality principle in physics, and the nature of instantaneous jumps make it impractical, if not impossible, to deal with in interacting systems. The resolution of instantaneous jumps in overdamped Langevin dynamics (of ABP, RTP, AOUP) was discussed by Fodor et al [35], while active matter models based on Lévy flights were proposed in Cairoli and Lee [36]. On the other hand, Lévy walks involve particles that change direction at random times, but travel in each direction with bounded (e.g., constant) velocity for a persistent time sampled from a heavy-tailed distribution.…”

Section: Introductionmentioning

confidence: 99%

Distribution and pressure of active Lévy swimmers under confinement

Zhou¹,

Peng²,

Gulian³

et al. 2021

J. Phys. A: Math. Theor.

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Many active matter systems are known to perform Lévy walks during migration or foraging. Such superdiffusive transport indicates long-range correlated dynamics. These behavior patterns have been observed for microswimmers such as bacteria in microfluidic experiments, where Gaussian noise assumptions are insufficient to explain the data. We introduce active Lévy swimmers to model such behavior. The focus is on ideal swimmers that only interact with the walls but not with each other, which reduces to the classical Lévy walk model but now under confinement. We study the density distribution in the channel and force exerted on the walls by the Lévy swimmers, where the boundaries require proper explicit treatment. We analyze stronger confinement via a set of coupled kinetics equations and the swimmers' stochastic trajectories. Previous literature demonstrated that power-law scaling in a multiscale analysis in free space results in a fractional diffusion equation. We show that in a channel, in the weak confinement limit active Lévy swimmers are governed by a modified Riesz fractional derivative. Leveraging recent results on fractional fluxes, we derive steady state solutions for the bulk density distribution of active Lévy swimmers in a channel, and demonstrate that these solutions agree well with particle simulations. The profiles are non-uniform over the entire domain, in contrast to constant-in-thebulk profiles of active Brownian and run-and-tumble particles. Our theory provides a mathematical framework for Lévy walks under confinement with sliding no-flux boundary conditions and provides a foundation for studies of interacting active Lévy swimmers.

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Non-Gaussian noise without memory in active matter

Cited by 25 publications

References 87 publications

Autonomous Engines Driven by Active Matter: Energetics and Design Principles

Autonomous Engines Driven by Active Matter: Energetics and Design Principles

Tuning the performance of a micrometer-sized Stirling engine through reservoir engineering

Distribution and pressure of active Lévy swimmers under confinement

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