Topological entanglement entropy of fracton stabilizer codes

PHYSICAL REVIEW B 97 (2018) ARTN 125101

H Ma, AT Schmitz, SA Parameswaran, M Hermele, RM Nandkishore

Phoresis and Enhanced Diffusion Compete in Enzyme Chemotaxis

Nano Letters 18 (2018) 2711-2717

J Agudo-Canalejo, P Illien, R Golestanian

© 2018 American Chemical Society. Chemotaxis of enzymes in response to gradients in the concentration of their substrate has been widely reported in recent experiments, but a basic understanding of the process is still lacking. Here, we develop a microscopic theory for chemotaxis that is valid for enzymes and other small molecules. Our theory includes both nonspecific interactions between enzyme and substrate as well as complex formation through specific binding between the enzyme and the substrate. We find that two distinct mechanisms contribute to enzyme chemotaxis: a diffusiophoretic mechanism due to the nonspecific interactions and a new type of mechanism due to binding-induced changes in the diffusion coefficient of the enzyme. The latter chemotactic mechanism points toward lower substrate concentration if the substrate enhances enzyme diffusion and toward higher substrate concentration if the substrate inhibits enzyme diffusion. For a typical enzyme, attractive phoresis and binding-induced enhanced diffusion will compete against each other. We find that phoresis dominates above a critical substrate concentration, whereas binding-induced enhanced diffusion dominates for low substrate concentration. Our results resolve an apparent contradiction regarding the direction of urease chemotaxis observed in experiments and, in general, clarify the relation between the enhanced diffusion and the chemotaxis of enzymes. Finally, we show that the competition between the two distinct chemotactic mechanisms may be used to engineer nanomachines that move toward or away from regions with a specific substrate concentration.

Interpretation of thermal conductance of the v=5/2 edge

PHYSICAL REVIEW B 97 (2018) ARTN 121406

SH Simon

Correlation function diagnostics for type-I fracton phases

PHYSICAL REVIEW B 97 (2018) ARTN 041110

T Devakul, SA Parameswaran, SL Sondhi

Finite-temperature dynamics of the Mott insulating Hubbard chain

PHYSICAL REVIEW B 97 (2018) ARTN 045146

A Nocera, FHL Essler, AE Feiguin

Current fluctuations across a nano-pore

Journal of Physics Condensed Matter 30 (2018)

M Zorkot, R Golestanian

© 2018 IOP Publishing Ltd. The frequency-dependent spectrum of current fluctuations through nano-scale channels is studied using analytical and computational techniques. Using a stochastic Nernst-Planck description and neglecting the interactions between the ions inside the channel, an expression is derived for the current fluctuations, assuming that the geometry of the channel can be incorporated through the lower limits for various wave-vector modes. Since the resulting expression turns out to be quite complex, a number of further approximations are discussed such that relatively simple expressions can be used for practical purposes. The analytical results are validated using Langevin dynamics simulations.

Shape dependent phoretic propulsion of slender active particles


Y Ibrahim, R Golestanian, TB Liverpool

Structure of edge-state inner products in the fractional quantum Hall effect

PHYSICAL REVIEW B 97 (2018) ARTN 155108

R Fern, R Bondesan, SH Simon

Clustering of Magnetic Swimmers in a Poiseuille Flow.

Physical review letters 120 (2018) 188101-

F Meng, D Matsunaga, R Golestanian

We investigate the collective behavior of magnetic swimmers, which are suspended in a Poiseuille flow and placed under an external magnetic field, using analytical techniques and Brownian dynamics simulations. We find that the interplay between intrinsic activity, external alignment, and magnetic dipole-dipole interactions leads to longitudinal structure formation. Our work sheds light on a recent experimental observation of a clustering instability in this system.

Critical behavior of the extended Hubbard model with bond dimerization

Physica B: Condensed Matter 536 (2018) 474-478

S Ejima, F Lange, FHL Essler, H Fehske

© 2017 Elsevier B.V. Exploiting the matrix-product-state based density-matrix renormalization group (DMRG) technique we study the one-dimensional extended (U-V) Hubbard model with explicit bond dimerization in the half-filled band sector. In particular we investigate the nature of the quantum phase transition, taking place with growing ratio V/U between the symmetry-protected-topo logical and charge-density-wave insulating states. The (weak-coupling) critical line of continuous Ising transitions with central charge c=1/2 terminates at a tricritical point belonging to the universality class of the dilute Ising model with c=7/10. We demonstrate that our DMRG data perfectly match with (tricritical) Ising exponents, e.g., for the order parameter β=1/8 (1/24) and correlation length ν=1 (5/9). Beyond the tricritical Ising point, in the strong-coupling regime, the quantum phase transition becomes first order.

Dynamics of a Lattice Gauge Theory with Fermionic Matter -- Minimal Quantum Simulator with Time-Dependent Impurities in Ultracold Gases

arXiv (2018)

D Kovrizhin, A Smith, J Knolle, R Moessner

We propose a minimal cold atomic gas quantum simulator for studying the real-time dynamics of a Z2 lattice gauge theory minimally coupled to fermionic matter. Using duality transformations we show that dynamical correlators of the gauge field can be obtained by measuring the dynamics of two pairs of impurities in a lattice of free fermions. We provide a protocol for the implementation of this minimal setting in a cold atomic gas experiment and predict a number of unusual experimental features in the integrable limit of the gauge theory. Finally, we show how the experimental setting can easily be extended to non-integrable regimes for exploring strongly interacting gauge theories beyond the capabilities of classical computers.

Dynamical Localization in Z2 Lattice Gauge Theories

arXiv (2018)

D Kovrizhin, A Smith, J Knolle, R Moessner

We study quantum quenches in two-dimensional lattice gauge theories with fermions coupled to dynamical Z2 gauge fields. Through the identification of an extensive set of conserved quantities, we propose a generic mechanism of charge localization in the absence of quenched disorder both in the Hamiltonian and in the initial states. We provide diagnostics of this localization through a set of experimentally relevant dynamical measures, entanglement measures, as well as spectral properties of the model. One of the defining features of the models which we study is a binary nature of emergent disorder, related to Z2 degrees of freedom. This results in a qualitatively different behaviour in the strong disorder limit compared to typically studied models of localization. For example it gives rise to a possibility of delocalization transition via a mechanism of quantum percolation in dimensions higher than 1D. We highlight the importance of our general phenomenology to questions related to dynamics of defects in Kitaev's toric code, and to quantum quenches in Hubbard models. While the simplest models we consider are effectively non-interacting, we also include interactions leading to many-body localization-like logarithmic entanglement growth. Finally, we consider effects of interactions which generate dynamics for conserved charges, which gives rise to only transient localization behaviour, or quasi-many-body-localization.

Multigenerational memory and adaptive adhesion in early bacterial biofilm communities.

Proceedings of the National Academy of Sciences of the United States of America 115 (2018) 4471-4476

CK Lee, J de Anda, AE Baker, RR Bennett, Y Luo, EY Lee, JA Keefe, JS Helali, J Ma, K Zhao, R Golestanian, GA O'Toole, GCL Wong

Using multigenerational, single-cell tracking we explore the earliest events of biofilm formation by Pseudomonas aeruginosa During initial stages of surface engagement (≤20 h), the surface cell population of this microbe comprises overwhelmingly cells that attach poorly (∼95% stay <30 s, well below the ∼1-h division time) with little increase in surface population. If we harvest cells previously exposed to a surface and direct them to a virgin surface, we find that these surface-exposed cells and their descendants attach strongly and then rapidly increase the surface cell population. This "adaptive," time-delayed adhesion requires determinants we showed previously are critical for surface sensing: type IV pili (TFP) and cAMP signaling via the Pil-Chp-TFP system. We show that these surface-adapted cells exhibit damped, coupled out-of-phase oscillations of intracellular cAMP levels and associated TFP activity that persist for multiple generations, whereas surface-naïve cells show uncorrelated cAMP and TFP activity. These correlated cAMP-TFP oscillations, which effectively impart intergenerational memory to cells in a lineage, can be understood in terms of a Turing stochastic model based on the Pil-Chp-TFP framework. Importantly, these cAMP-TFP oscillations create a state characterized by a suppression of TFP motility coordinated across entire lineages and lead to a drastic increase in the number of surface-associated cells with near-zero translational motion. The appearance of this surface-adapted state, which can serve to define the historical classification of "irreversibly attached" cells, correlates with family tree architectures that facilitate exponential increases in surface cell populations necessary for biofilm formation.

Trial wave functions for a composite Fermi liquid on a torus

PHYSICAL REVIEW B 97 (2018) ARTN 035149

M Fremling, N Moran, JK Slingerland, SH Simon

Recoverable information and emergent conservation laws in fracton stabilizer codes

PHYSICAL REVIEW B 97 (2018) ARTN 134426

AT Schmitz, H Ma, RM Nandkishore, SA Parameswaran

Size constraints on a Majorana beam-splitter interferometer: Majorana coupling and surface-bulk scattering

PHYSICAL REVIEW B 97 (2018) ARTN 115424

HS Roising, SH Simon

Condensation-driven phase transitions in perturbed string nets

Physical Review B 96 (2017)

M Mariën, J Haegeman, P Fendley, F Verstraete

The macroscopic pancake bounce


JA Bro, KSB Jensen, AN Larsen, JM Yeomans, T Hecksher

Synchronization and collective dynamics of flagella and cilia as hydrodynamically coupled oscillators

Journal of the Physical Society of Japan 86 (2017)

N Uchida, R Golestanian, RR Bennett

©2017 The Physical Society of Japan. Cooperative motion of flagella and cilia faciliates swimming of microorganisms and material transport in the body of multicellular organisms. Using minimal models, we address the roles of hydrodynamic interaction in synchronization and collective dynamics of flagella and cilia. Collective synchronization of bacterial flagella is studied with a model of bacterial carpets. Cilia and eukaryotic flagella are characterized by periodic modulation of their driving forces, which produces various patterns of two-body synchronization and metachronal waves. Long-range nature of the interaction introduces novel features in the dynamics of these model systems. The flagella of a swimmer synchronize also by a viscous drag force mediated through the swimmer’s body. Recent advance in experimental studies of the collective dynamics of flagella, cilia and related artificial systems are summarized.

Biopolymer dynamics driven by helical flagella


AK Balin, A Zottl, JM Yeomans, TN Shendruk