# Publications

## Topological entanglement entropy of fracton stabilizer codes

PHYSICAL REVIEW B **97** (2018) ARTN 125101

## Correlation function diagnostics for type-I fracton phases

PHYSICAL REVIEW B **97** (2018) ARTN 041110

## Finite-temperature dynamics of the Mott insulating Hubbard chain

PHYSICAL REVIEW B **97** (2018) ARTN 045146

## Current fluctuations across a nano-pore

Journal of Physics Condensed Matter **30** (2018)

© 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

PHYSICAL REVIEW FLUIDS **3** (2018) ARTN 033101

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

PHYSICAL REVIEW B **97** (2018) ARTN 155108

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

arXiv (2018)

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)

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 (2018)

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

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

PHYSICAL REVIEW B **97** (2018) ARTN 115424

## High-Speed 4D Computational Microscopy of Bacterial Surface Motility

ACS Nano **11** (2017) 9340-9351

© 2017 American Chemical Society. Bacteria exhibit surface motility modes that play pivotal roles in early-stage biofilm community development, such as type IV pili-driven "twitching" motility and flagellum-driven "spinning" and "swarming" motility. Appendage-driven motility is controlled by molecular motors, and analysis of surface motility behavior is complicated by its inherently 3D nature, the speed of which is too fast for confocal microscopy to capture. Here, we combine electromagnetic field computation and statistical image analysis to generate 3D movies close to a surface at 5 ms time resolution using conventional inverted microscopes. We treat each bacterial cell as a spherocylindrical lens and use finite element modeling to solve Maxwell's equations and compute the diffracted light intensities associated with different angular orientations of the bacterium relative to the surface. By performing cross-correlation calculations between measured 2D microscopy images and a library of computed light intensities, we demonstrate that near-surface 3D movies of Pseudomonas aeruginosa translational and rotational motion are possible at high temporal resolution. Comparison between computational reconstructions and detailed hydrodynamic calculations reveals that P. aeruginosa act like low Reynolds number spinning tops with unstable orbits, driven by a flagellum motor with a torque output of ~2 pN μm. Interestingly, our analysis reveals that P. aeruginosa can undergo complex flagellum-driven dynamical behavior, including precession, nutation, and an unexpected taxonomy of surface motility mechanisms, including upright-spinning bacteria that diffuse laterally across the surface, and horizontal bacteria that follow helicoidal trajectories and exhibit superdiffusive movements parallel to the surface.

## Long coherence times for edge spins

Journal of Statistical Mechanics: Theory and Experiment **2017** (2017) 063105-063105

## Electric-field-induced shape transition of nematic tactoids.

Physical review. E **96** (2017) 022706-

The occurrence of new textures of liquid crystals is an important factor in tuning their optical and photonics properties. Here, we show, both experimentally and by numerical computation, that under an electric field chitin tactoids (i.e., nematic droplets) can stretch to aspect ratios of more than 15, leading to a transition from a spindlelike to a cigarlike shape. We argue that the large extensions occur because the elastic contribution to the free energy is dominated by the anchoring. We demonstrate that the elongation involves hydrodynamic flow and is reversible: the tactoids return to their original shapes upon removing the field.

## Focusing and Sorting of Ellipsoidal Magnetic Particles in Microchannels.

Physical review letters **119** (2017) 198002-

We present a simple method to control the position of ellipsoidal magnetic particles in microchannel Poiseuille flow at low Reynolds number using a static uniform magnetic field. The magnetic field is utilized to pin the particle orientation, and the hydrodynamic interactions between ellipsoids and channel walls allow control of the transverse position of the particles. We employ a far-field hydrodynamic theory and simulations using the boundary element method and Brownian dynamics to show how magnetic particles can be focused and segregated by size and shape. This is of importance for particle manipulation in lab-on-a-chip devices.

## Frontiers of chaotic advection

REVIEWS OF MODERN PHYSICS **89** (2017) ARTN 025007

## 'Fuelled' motion: Phoretic motility and collective behaviour of active colloids

Chemical Society Reviews **46** (2017) 5508-5518

© The Royal Society of Chemistry 2017. Designing microscopic and nanoscopic self-propelled particles and characterising their motion have become a major scientific challenge over the past few decades. To this purpose, phoretic effects, namely propulsion mechanisms relying on local field gradients, have been the focus of many theoretical and experimental studies. In this review, we adopt a tutorial approach to present the basic physical mechanisms at stake in phoretic motion, and describe the different experimental works that led to the fabrication of active particles based on this principle. We also present the collective effects observed in assemblies of interacting active colloids, and the theoretical tools that have been used to describe phoretic and hydrodynamic interactions.

## Multiple phoretic mechanisms in the self-propulsion of a Pt-insulator Janus swimmer

JOURNAL OF FLUID MECHANICS **828** (2017) 318-352

## Quantum disentangled liquid in the half-filled Hubbard model

PHYSICAL REVIEW B **96** (2017) ARTN 195153