Self-consistent time-dependent harmonic approximation for the sine-Gordon model out of equilibrium


YD van Nieuwkerk, FHL Essler

Eigenstate Correlations, Thermalization and the Butterfly Effect

Physical Review Letters American Physical Society (2019)


Almost strong (0, pi) edge modes in clean interacting one-dimensional Floquet systems

PHYSICAL REVIEW B 99 (2019) ARTN 205419

DJ Yates, FHL Essler, A Mitrai

Erratum: Charge Transport in Weyl Semimetals (Physical Review Letters (2012) 108 (046602) DOI: 10.1103/PhysRevLett.108.046602)

Physical Review Letters 123 (2019)

P Hosur, SA Parameswaran, A Vishwanath

© 2019 American Physical Society. This erratum corrects errors in numerical factors in Eqs. (1), (7), and (8), and the overall scale of the dc resistivity plotted in Fig. 2. We recently discovered an algebraic error in Eq. (7), which led to incorrect numerical factors in Eqs. (1) and (8). The correct Eqs. (1), (7) and (8), respectively, are (Formula Presented). An error was also found in the overall scale of pdc = 1/σdc calculated from (1) and plotted in Fig. 2 of the Letter. With these corrections our theory underestimates ?dc of the samples in Ref. [12] of the Letter, which is understandable since the samples are polycrystalline while our theory specializes to single crystals. However, correcting both errors gives excellent agreement with recent experiments on Eu 0.96 Bi 0.04 Ir 2 O 7 [1] for reasonable values of parameters, as shown in Fig. 1. Moreover, Ref. [1] finds pdc ( T ) ∼ 1 / T , as predicted by our theory, only at low temperatures, which is where our theory is best applicable since it contains only Coulomb scattering but ignores phonon scattering. Thus, it is likely that the low-temperature transport in Eu 0.96 Bi 0.04 Ir 2 O 7 is dominated by Coulomb scattering. We thank Surjeet Singh and Prachi Telang for bringing the error in the computation of pdc to our attention (Figure Presented).

Flagella-like Beating of a Single Microtubule.

Nano letters 19 (2019) 3359-3363

A Vilfan, S Subramani, E Bodenschatz, R Golestanian, I Guido

Kinesin motors can induce a buckling instability in a microtubule with a fixed minus end. Here we show that by modifying the surface with a protein-repellent functionalization and using clusters of kinesin motors, the microtubule can exhibit persistent oscillatory motion resembling the beating of sperm flagella. The observed period is of the order of 1 min. From the experimental images we theoretically determine a distribution of motor forces that explains the observed shapes using a maximum likelihood approach. A good agreement is achieved with a small number of motor clusters acting simultaneously on a microtubule. The tangential forces exerted by a cluster are mostly in the range 0-8 pN toward the microtubule minus end, indicating the action of 1 or 2 kinesin motors. The lateral forces are distributed symmetrically and mainly below 10 pN, while the lateral velocity has a strong peak around zero. Unlike well-known models for flapping filaments, kinesins are found to have a strong "pinning" effect on the beating filaments. Our results suggest new strategies to utilize molecular motors in dynamic roles that depend sensitively on the stress built-up in the system.

NMR relaxation in Ising spin chains

PHYSICAL REVIEW B 99 (2019) ARTN 035156

J Steinberg, NP Armitage, FHL Essler, S Sachdev

Signatures of the many-body localized regime in two dimensions

NATURE PHYSICS 15 (2019) 164-169

TB Wahl, A Pal, SH Simon

Topology- and symmetry-protected domain wall conduction in quantum Hall nematics

PHYSICAL REVIEW B 100 (2019) ARTN 165103

K Agarwal, MT Randeria, A Yazdani, SL Sondhi, SA Parameswaran

Active Phase Separation in Mixtures of Chemically Interacting Particles.

Physical review letters 123 (2019) 018101-

J Agudo-Canalejo, R Golestanian

We theoretically study mixtures of chemically interacting particles, which produce or consume a chemical to which they are attracted or repelled, in the most general case of many coexisting species. We find a new class of active phase separation phenomena in which the nonequilibrium chemical interactions between particles, which break action-reaction symmetry, can lead to separation into phases with distinct density and stoichiometry. Because of the generic nature of our minimal model, our results shed light on the underlying fundamental principles behind nonequilibrium self-organization of cells and bacteria, catalytic enzymes, or phoretic colloids.

Active phase separation in mixtures of chemically-interacting particles


J Agudo-Canalejo, R Golestanian

Active phase separation in mixtures of chemically-interacting particles


J Agudo-Canalejo, R Golestanian

Controlling collective rotational patterns of magnetic rotors.

Nature communications 10 (2019) 4696-

D Matsunaga, JK Hamilton, F Meng, N Bukin, EL Martin, FY Ogrin, JM Yeomans, R Golestanian

Magnetic actuation is widely used in engineering specific forms of controlled motion in microfluidic applications. A challenge, however, is how to extract different desired responses from different components in the system using the same external magnetic drive. Using experiments, simulations, and theoretical arguments, we present emergent rotational patterns in an array of identical magnetic rotors under an uniform, oscillating magnetic field. By changing the relative strength of the external field strength versus the dipolar interactions between the rotors, different collective modes are selected by the rotors. When the dipole interaction is dominant the rotors swing upwards or downwards in alternating stripes, reflecting the spin-ice symmetry of the static configuration. For larger spacings, when the external field dominates over the dipolar interactions, the rotors undergo full rotations, with different quarters of the array turning in different directions. Our work sheds light on how collective behaviour can be engineered in magnetic systems.

Eigenstate Correlations, Thermalization, and the Butterfly Effect.

Physical review letters 122 (2019) 220601-

A Chan, A De Luca, JT Chalker

We discuss eigenstate correlations for ergodic, spatially extended many-body quantum systems, in terms of the statistical properties of matrix elements of local observables. While the eigenstate thermalization hypothesis (ETH) is known to give an excellent description of these quantities, the phenomenon of scrambling and the butterfly effect imply structure beyond ETH. We determine the universal form of this structure at long distances and small eigenvalue separations for Floquet systems. We use numerical studies of a Floquet quantum circuit to illustrate both the accuracy of ETH and the existence of our predicted additional correlations.

Emergence of Active Nematic Behavior in Monolayers of Isotropic Cells.

Physical review letters 122 (2019) 048004-048004

R Mueller, JM Yeomans, A Doostmohammadi

There is now growing evidence of the emergence and biological functionality of liquid crystal features, including nematic order and topological defects, in cellular tissues. However, how such features that intrinsically rely on particle elongation emerge in monolayers of cells with isotropic shapes is an outstanding question. In this Letter, we present a minimal model of cellular monolayers based on cell deformation and force transmission at the cell-cell interface that explains the formation of topological defects and captures the flow-field and stress patterns around them. By including mechanical properties at the individual cell level, we further show that the instability that drives the formation of topological defects, and leads to active turbulence, emerges from a feedback between shape deformation and active driving. The model allows us to suggest new explanations for experimental observations in tissue mechanics, and to propose designs for future experiments.

Exact solution of a percolation analog for the many-body localization transition

PHYSICAL REVIEW B 99 (2019) ARTN 220201

S Roy, DE Logan, JT Chalker

Pairing, waltzing and scattering of chemotactic active colloids


S Saha, S Ramaswamy, R Golestanian

Magnetic Excitations of the Classical Spin Liquid MgCr2O4


X Bai, JAM Paddison, E Kapit, SM Koohpayeh, J-J Wen, SE Dutton, AT Savici, AI Kolesnikov, GE Granroth, CL Broholm, JT Chalker, M Mourigal

Signatures of information scrambling in the dynamics of the entanglement spectrum

PHYSICAL REVIEW B 100 (2019) ARTN 125115

T Rakovszky, S Gopalakrishnan, SA Parameswaran, F Pollmann

Trail-mediated self-interaction.

The Journal of chemical physics 150 (2019) 214111-

WT Kranz, R Golestanian

A number of microorganisms leave persistent trails while moving along surfaces. For single-cell organisms, the trail-mediated self-interaction will influence the dynamics. It has been discussed recently [Kranz et al., Phys. Rev. Lett. 117, 038101 (2016)] that the self-interaction may localize the organism above a critical coupling χc to the trail. Here, we will derive a generalized active particle model capturing the key features of the self-interaction and analyze its behavior for smaller couplings χ < χc. We find that fluctuations in propulsion speed shift the localization transition to stronger couplings.

Tunable self-healing of magnetically propelling colloidal carpets.

Nature communications 10 (2019) 2444-

H Massana-Cid, F Meng, D Matsunaga, R Golestanian, P Tierno

The process of crystallization is difficult to observe for transported, out-of-equilibrium systems, as the continuous energy injection increases activity and competes with ordering. In emerging fields such as microfluidics and active matter, the formation of long-range order is often frustrated by the presence of hydrodynamics. Here we show that a population of colloidal rollers assembled by magnetic fields into large-scale propelling carpets can form perfect crystalline materials upon suitable balance between magnetism and hydrodynamics. We demonstrate a field-tunable annealing protocol based on a controlled colloidal flow above the carpet that enables complete crystallization after a few seconds of propulsion. The structural transition from a disordered to a crystalline carpet phase is captured via spatial and temporal correlation functions. Our findings unveil a novel pathway to magnetically anneal clusters of propelling particles, bridging driven systems with crystallization and freezing in material science.