Chemotactic self-caging in active emulsions.

Proceedings of the National Academy of Sciences of the United States of America 119:24 (2022) e2122269119

Authors:

Babak Vajdi Hokmabad, Jaime Agudo-Canalejo, Suropriya Saha, Ramin Golestanian, Corinna C Maass

Abstract:

A common feature of biological self-organization is how active agents communicate with each other or their environment via chemical signaling. Such communications, mediated by self-generated chemical gradients, have consequences for both individual motility strategies and collective migration patterns. Here, in a purely physicochemical system, we use self-propelling droplets as a model for chemically active particles that modify their environment by leaving chemical footprints, which act as chemorepulsive signals to other droplets. We analyze this communication mechanism quantitatively both on the scale of individual agent-trail collisions as well as on the collective scale where droplets actively remodel their environment while adapting their dynamics to that evolving chemical landscape. We show in experiment and simulation how these interactions cause a transient dynamical arrest in active emulsions where swimmers are caged between each other's trails of secreted chemicals. Our findings provide insight into the collective dynamics of chemically active particles and yield principles for predicting how negative autochemotaxis shapes their navigation strategy.

A topological fluctuation theorem.

Nature communications 13:1 (2022) 3036

Authors:

Benoît Mahault, Evelyn Tang, Ramin Golestanian

Abstract:

Fluctuation theorems specify the non-zero probability to observe negative entropy production, contrary to a naive expectation from the second law of thermodynamics. For closed particle trajectories in a fluid, Stokes theorem can be used to give a geometric characterization of the entropy production. Building on this picture, we formulate a topological fluctuation theorem that depends only by the winding number around each vortex core and is insensitive to other aspects of the force. The probability is robust to local deformations of the particle trajectory, reminiscent of topologically protected modes in various classical and quantum systems. We demonstrate that entropy production is quantized in these strongly fluctuating systems, and it is controlled by a topological invariant. We demonstrate that the theorem holds even when the probability distributions are non-Gaussian functions of the generated heat.

The long and winding road to understanding organismal construction: Reply to comments on "From genotypes to organisms: State-of-the-art and perspectives of a cornerstone in evolutionary dynamics".

Physics of life reviews 42 (2022) 19-24

Authors:

Susanna Manrubia, José A Cuesta, Jacobo Aguirre, Sebastian E Ahnert, Lee Altenberg, Alejandro V Cano, Pablo Catalán, Ramon Diaz-Uriarte, Santiago F Elena, Juan Antonio García-Martín, Paulien Hogeweg, Bhavin S Khatri, Joachim Krug, Ard A Louis, Nora S Martin, Joshua L Payne, Matthew J Tarnowski, Marcel Weiß

Stochastic strong zero modes and their dynamical manifestations

ArXiv 2205.0911 (2022)

Authors:

Katja Klobas, Paul Fendley, Juan P Garrahan

One-dimensional Luttinger liquids in a two-dimensional moiré lattice

Nature Springer Nature 605:7908 (2022) 57-62

Authors:

Pengjie Wang, Guo Yu, Yves H Kwan, Yanyu Jia, Shiming Lei, Sebastian Klemenz, F Alexandre Cevallos, Ratnadwip Singha, Trithep Devakul, Kenji Watanabe, Takashi Taniguchi, Shivaji L Sondhi, Robert J Cava, Leslie M Schoop, Siddharth A Parameswaran, Sanfeng Wu

Abstract:

The Luttinger liquid (LL) model of one-dimensional (1D) electronic systems provides a powerful tool for understanding strongly correlated physics, including phenomena such as spin–charge separation1. Substantial theoretical efforts have attempted to extend the LL phenomenology to two dimensions, especially in models of closely packed arrays of 1D quantum wires2,3,4,5,6,7,8,9,10,11,12,13, each being described as a LL. Such coupled-wire models have been successfully used to construct two-dimensional (2D) anisotropic non-Fermi liquids2,3,4,5,6, quantum Hall states7,8,9, topological phases10,11 and quantum spin liquids12,13. However, an experimental demonstration of high-quality arrays of 1D LLs suitable for realizing these models remains absent. Here we report the experimental realization of 2D arrays of 1D LLs with crystalline quality in a moiré superlattice made of twisted bilayer tungsten ditelluride (tWTe2). Originating from the anisotropic lattice of the monolayer, the moiré pattern of tWTe2 hosts identical, parallel 1D electronic channels, separated by a fixed nanoscale distance, which is tuneable by the interlayer twist angle. At a twist angle of approximately 5 degrees, we find that hole-doped tWTe2 exhibits exceptionally large transport anisotropy with a resistance ratio of around 1,000 between two orthogonal in-plane directions. The across-wire conductance exhibits power-law scaling behaviours, consistent with the formation of a 2D anisotropic phase that resembles an array of LLs. Our results open the door for realizing a variety of correlated and topological quantum phases based on coupled-wire models and LL physics.