arXiv subjects

Adrià Garcés

Publications and source records attributed to Adrià Garcés.

4 recordsLinked to original sources

arXiv2026

Universal transport of active colloids with sensory delay in motility landscapes

We experimentally, numerically and analytically explore the diffusive transport of active colloidal particles with sensory delay, navigating motility landscapes in which the self-propulsion speed depends on space. We show how the transport properties can be obtained by replacing the space dependence of the self-propulsion speed by a dynamical stochastic switching process in the absence of delay, and extend the theory for systems with finite delayed responses. We obtain analytical results for the mean square displacement and the effective diffusion coefficient which accurately predict experimental measurements and numerical simulations across multiple scales. We show how, within the regime of validity of the delay-extended theory, density patterns and effective diffusion obey universal scaling forms. Our work provides minimal framework describing the transport properties of active swimmers with internal adaptation dynamics in motility landscapes.

cond-mat.stat-mech↗

arXiv2026

Time irreversibility and entropy production in non-Hermitian Model A field theories

We develop a systematic framework to quantify irreversibility in scalar Model A field theories with a generic non-Hermitian term driving the dynamics. Using the stochastic path-integral formalism, we perform a controlled small-noise expansion, allowing the computation of the entropy production rate (EPR) and violations of the fluctuation-dissipation theorem (FDT). We show that the local EPR is entirely determined by the anti-Hermitian part of the linearised Langevin equation. Around steady states, the non-Hermitian component produces linear corrections to FDT violations and contributes quadratically to the EPR. As an illustration of the applicability of our approach, we analyse a minimal non-Hermitian extension of the Ginzburg-Landau $ψ^4$ theory describing a non-reciprocal Ising model at coarse-grained scales, for which we obtain explicit expressions of the local EPR, showing that it localises at interfaces in non-uniform states. Our results provide a general characterisation of TRS breaking in non-Hermitian scalar field theories.

cond-mat.stat-mech↗

arXiv2025

Depinning and activated motion of chiral self-propelled robots

We study experimentally, numerically and analytically, the dynamics of a chiral active particle (cm-sized robots), pulled at a constant translational velocity. We show that the system can be mapped to a Brownian particle driven across a periodic potential landscape, and thus exhibits a rotational depinning transition in the noiseless limit, giving rise to a creep regime in the presence of rotational diffusion. We show that a simple model of chiral, self-aligning, active particles accurately describes such dynamics. The steady-state distribution and escape times from local potential barriers, corresponding to long-lived orientations of the particles, can be computed exactly within the model and is in excellent agreement with both experiments and particle-based simulations, with no fitting parameters. Our work thus consolidates such self-propelled robots as a model system for the study of chiral active matter, and highlights the interesting dynamics arising from the interplay between external and internal driving forces in the presence of a self-aligning torque.

cond-mat.stat-mech↗

arXiv2024

Phase Transitions in single species Ising Models with Non-Reciprocal couplings

We present a general framework for incorporating non-reciprocal interactions into the Ising model with Glauber dynamics, without requiring multiple species. We then focus on a model with vision-cone type interactions. We solve it in a fully connected network (mean-field) and perform extensive numerical simulations of the model in the square lattice. We find that the breakdown of the spin-flip symmetry introduced by non-reciprocity induces a discontinuous phase transition on top of the usual continuous one, that eventually occurs at higher critical temperatures. Combining a static and dynamic scaling analysis, we measure the critical exponents associated to the continuous symmetry breaking transition, and find them to be identical to the ones of the Ising model in two dimensions (2D), with the exception of the exponent $β$ associated to the order parameter. The latter appears to increase as the non-reciprocity of the coupling increases, suggesting that, within our numerical precision, the model does not belong to the 2D Ising model universality class. The coarsening process is anisotropic, but still follows the usual dynamic scaling with an exponent compatible with the standard value with non-conserved order parameter dynamics.

cond-mat.stat-mech↗