Paul M Chaikin

In photonic crystals the propagation of light is governed by their photonic band structure, an ensemble of propagating states grouped into bands, separated by photonic band gaps. Due to discrete symmetries in spatially strictly periodic dielectric structures their photonic band structure is intrinsically anisotropic. However, for many applications, such as manufacturing artificial structural color materials or developing photonic computing devices, but also for the fundamental understanding of light-matter interactions, it is of major interest to seek materials with long range non-periodic dielectric structures which allow the formation of {\it isotropic} photonic band gaps. Here, we report the first ever 3D isotropic photonic band gap for an optimized disordered stealthy hyperuniform structure for microwaves. The transmission spectra are directly compared to a diamond pattern and an amorphous structure with similar node density. The band structure is measured experimentally for all three microwave structures, manufactured by 3D-Laser-printing for meta-materials with refractive index up to . Results agree well with finite-difference-time-domain numerical investigations and a priori calculations of the band-gap for the hyperuniform structure: the diamond structure shows gaps but being anisotropic as expected, the stealthy hyperuniform pattern shows an isotropic gap of very similar magnitude, while the amorphous structure does not show a gap at all. The centimeter scaled microwave structures may serve as prototypes for micrometer scaled structures with bandgaps in the technologically very interesting region of infrared (IR).

Social physics explores responses to information exchange in a social network, and can be mapped down to bacterial collective signaling. Here, we explore how social inter-bacterial communication includes coordination of response to communication loss, as opposed to solitary searching for food, with collective response emergence at the population level. We present a 2-dimensional enclosed microfluidic environment that utilizes concentric rings of funnel ratchets, which direct motile E.coli bacteria towards a sole exit hole, an information ``black hole'', passage into the black hole irreversibly sweeps the bacteria away via hydrodynamic flow. We show that the spatiotemporal evolution of entropy production reveals how bacteria avoid crossing the hydrodynamic black hole information horizon.

The invention of DNA nanotechnology has enabled molecular computation as a promising substitute for traditional semiconductors which are limited to two-dimensional architectures and by heating problems resulting from densification. Current studies of logic gates achieved by DNA molecules are predominately focused on two-state operations (AND, OR, etc.); however, realizing tri-state logic (high impedance Z) in DNA computation is understudied. Here we actively fold DNA origami chain-like hinged rods to induce conformational changes that return tri-state logic signals. We use rigid six helix-bundle (6HB) DNA origami to self-assemble a linear trimer chain as a circuit platform with functional single-stranded (ss) DNA near each semi-flexible hinge. The presence or absence of ssDNA enable and input strands allows hybridization to take place at the hinges, activating one-fold (0) or two-folds (1) from the straight …

Here we report the results of microgravity experiments performed on the International Space Station (ISS) to study crystallized, metastable colloidal liquids in the region of the hard sphere phase diagram that has been found to be glassy on Earth. Using confocal microscopy, we observed the self-assembly of high density, three-dimensional colloidal crystals from micron-size hard spheres suspended within a fluid medium. The largest face-centered cubic (FCC) phase measured 27 x 1.5 x 0.15 mm. From a practical aspect, the fact that a single, topological defect-free FCC colloidal crystal can be grown in microgravity and the crystal returned from orbit suggests new routes for manufacturing colloidal devices, particularly optical elements in space.

Driven systems composed largely of droplets and fuel make up a significant portion of microbiological function. At the micrometer scale, fully synthetic systems that perform an array of tasks within a uniform bulk are much more rare. In this work, we introduce an innovative design for solid-in-oil composite microdroplets. These microdroplets are engineered to nucleate an internal phase, undergo inflation, and eventually burst, all powered by a steady and uniform energy input. We show that by altering the background input, volumetric change and burst time can be tuned. When the inflated droplets release the inner contents, colloidal particles are shown to transiently attract to the release point. Lastly, we show that the system has the ability to perform multiple inflation–burst cycles. We anticipate that our conceptual design of internally powered microdroplets will catalyze further research into autonomous systems …

Here we study how a non-equilibrium 2D crystal undergoes melting as a function of activity. We use a system of charged particles confined to an oil-water interface forming a 2D lattice, a fraction of which have additional magnetic particles that sit directly below them and are rotated by an external magnetic field. This activity allows for the proliferation of topological defects, leading to melting of the 2D crystal. We characterize the nature of this melting transition and determine its order using conventional tools such as g 6 (r) and the local distribution of ψ 6. In addition, we use information theoretic approaches such as the computable information density (CID) and calculation of entropy production to gain further insight into the behavior of this non-equilibrium melting transition.

Nanoscale industrial robots have potential as manufacturing platforms and are capable of automatically performing repetitive tasks to handle and produce nanomaterials with consistent precision and accuracy. We demonstrate a DNA industrial nanorobot that fabricates a three-dimensional (3D), optically active chiral structure from optically inactive parts. By making use of externally controlled temperature and ultraviolet (UV) light, our programmable robot, ~100 nanometers in size, grabs different parts, positions and aligns them so that they can be welded, releases the construct, and returns to its original configuration ready for its next operation. Our robot can also self-replicate its 3D structure and functions, surpassing single-step templating (restricted to two dimensions) by using folding to access the third dimension and more degrees of freedom. Our introduction of multiple-axis precise folding and positioning as a …

Biased Random Organization (BRO) is a simple dynamical model that produces hyperuniform Random Close Packed (RCP) structures at its critical endpoint in 3D. BRO follows Manna universality class behavior, with an upper critical dimension of 4. We confirm mean field exponents for d>= 4 through analysis of the fraction of active states and the distribution of interparticle gaps. Through simulations, we show that monodisperse BRO systems in d= 3, 4, 5 recover RCP behavior at their critical endpoint with previously predicted packing fractions of φ= 0.64, 0.45, and 0.30 respectively. Additionally, we find BRO in d= 3, 4, 5 produces structures with their corresponding isostatic contact numbers Z= 6, 8, and 10. While bidisperse BRO in 2D produces hyperuniform and isostatic critical states, the monodisperse case instead produces a crystalline state as its critical endpoint. This leads us to conjecture that BRO produces …