Entropy production and collective excitations of crystals out of equilibrium: The concept of entropons

Caprini, L.; Marini Bettolo Marconi, U.; Löwen, H.

doi:10.1103/physreve.108.044603

Cited by 5 publications

(1 citation statement)

References 143 publications

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“…The interest of statistical physics in those systems is both at the level of a single active particle and at the level of large populations of active particles, since in both cases the lack of thermodynamic equilibrium triggers the appearance of unexpected phenomena [ 11 , 12 , 13 , 14 ]. A single self-propelling particle hides a complex arrangement of several internal degrees of freedom such as molecular motors actuating flagella, as in bacteria or sperms; it, therefore, may require nontrivial stochastic modeling, in contrast with passive Brownian particles [ 15 ].…”

Section: Introductionmentioning

confidence: 99%

Entropy Production of Run-and-Tumble Particles

Paoluzzi,

Puglisi,

Angelani

2024

Entropy

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We analyze the entropy production in run-and-tumble models. After presenting the general formalism in the framework of the Fokker–Planck equations in one space dimension, we derive some known exact results in simple physical situations (free run-and-tumble particles and harmonic confinement). We then extend the calculation to the case of anisotropic motion (different speeds and tumbling rates for right- and left-oriented particles), obtaining exact expressions of the entropy production rate. We conclude by discussing the general case of heterogeneous run-and-tumble motion described by space-dependent parameters and extending the analysis to the case of d-dimensional motions.

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Section: Introductionmentioning

confidence: 99%

Entropy Production of Run-and-Tumble Particles

Paoluzzi,

Puglisi,

Angelani

2024

Entropy

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Multiple temperatures and melting of a colloidal active crystal

Massana-Cid,

Maggi,

Gnan

et al. 2024

Nat Commun

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Thermal fluctuations constantly excite all relaxation modes in an equilibrium crystal. As the temperature rises, these fluctuations promote the formation of defects and eventually melting. In active solids, the self-propulsion of “atomic” units provides an additional source of non-equilibrium fluctuations whose effect on the melting scenario is still largely unexplored. Here we show that when a colloidal crystal is activated by a bath of swimming bacteria, solvent temperature and active temperature cooperate to define dynamic and thermodynamic properties. Our system consists of repulsive paramagnetic particles confined in two dimensions and immersed in a bath of light-driven E. coli. The relative balance between fluctuations and interactions can be adjusted in two ways: by changing the strength of the magnetic field and by tuning activity with light. When the persistence time of active fluctuations is short, a single effective temperature controls both the amplitudes of relaxation modes and the melting transition. For more persistent active noise, energy equipartition is broken and multiple temperatures emerge, whereas melting occurs before the Lindemann parameter reaches its equilibrium critical value. We show that this phenomenology is fully confirmed by numerical simulations and framed within a minimal model of a single active particle in a periodic potential.

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Enhancing (quasi-)long-range order in a two-dimensional driven crystal

Maire,

Plati

2024

The Journal of Chemical Physics

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It has been recently shown that 2D systems can exhibit crystalline phases with long-range translational order showcasing a striking violation of the Hohenberg–Mermin–Wagner (HMW) theorem, which is valid at equilibrium. This is made possible by athermal driving mechanisms that inject energy into the system without exciting long wavelength modes of the density field, thereby inducing hyperuniformity. However, as thermal fluctuations are superimposed on the non-equilibrium driving, long-range translational order is inevitably lost. Here, we discuss the possibility of exploiting non-equilibrium effects to suppress arbitrarily large density fluctuations even when a global thermal bath is coupled to the system. We introduce a model of a harmonic crystal driven both by a global thermal bath and by a momentum conserving noise, where the typical observables related to density fluctuations and long-range translational order can be analytically derived and put in relation. This model allows us to rationalize the violation of the HMW theorem observed in previous studies through the prediction of large-wavelength phonons, which thermalize at a vanishing effective temperature when the global bath is switched off. The conceptual framework introduced through this theory is then applied to numerical simulations of a hard-disk solid in contact with a thermal bath and driven out-of-equilibrium by active collisions. Our numerical analysis demonstrates how varying driving and dissipative parameters can lead to an arbitrary enhancement of the quasi-long-range order in the system regardless of the applied global noise amplitude. Finally, we outline a possible experimental procedure to apply our results to a realistic granular system.

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Entropy production and collective excitations of crystals out of equilibrium: The concept of entropons

Cited by 5 publications

References 143 publications

Entropy Production of Run-and-Tumble Particles

Entropy Production of Run-and-Tumble Particles

Multiple temperatures and melting of a colloidal active crystal

Enhancing (quasi-)long-range order in a two-dimensional driven crystal

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