Polaritonic states in a dielectric nanoguide: localization and strong coupling

Propagation of light through dielectrics lies at the heart of optics. However, this ubiquitous process is commonly described using phenomenological dielectric function $\varepsilon$ and magnetic permeability $\mu$, i.e. without addressing the quantum graininess of the dielectric matter. Here, we present a theoretical study where we consider a one-dimensional ensemble of atoms in a subwavelength waveguide (nanoguide) as fundamental building blocks of a model dielectric. By exploring the roles of the atom-waveguide coupling efficiency, density, disorder, and dephasing, we establish connections among various features of polaritonic light-matter states such as localization, super and subradiance, and strong coupling. In particular, we show that coherent multiple scattering of light among atoms that are coupled via a single propagating mode can gives rise to Rabi splitting. These results provide important insight into the underlying physics of strong coupling reported by recent room-temperature experiments with microcavities and surface plasmons.Comment: 10 pages, 6 figure

Coherent Interaction of Light and Single Molecules in a Dielectric Nanoguide

We present a new scheme for performing optical spectroscopy on single molecules. A glass capillary with a diameter of 600 nm filled with an organic crystal tightly guides the excitation light and provides a maximum spontaneous emission coupling factor ($\beta$) of 18% for the dye molecules doped in the organic crystal. Combination of extinction, fluorescence excitation and resonance fluorescence spectroscopy with microscopy provides high-resolution spatio-spectral access to a very large number of single molecules in a linear geometry. We discuss strategies for exploring a range of quantum optical phenomena, including coherent cooperative interactions in a mesoscopic ensemble of molecules mediated by a single mode of propagating photons.Comment: 5 pages, 5 figure

Design and synthesis of aromatic molecules for probing electric-fields at the nanoscale

We propose using halogenated organic dyes as nanoprobes for electric field and show their greatly enhanced Stark coefficients using density functional theory (DFT) calculations. We analyse halogenated variants of three molecules that have been of interest for cryogenic single molecule spectroscopy, perylene, terrylene, and dibenzoterrylene, with the zero-phonon optical transitions at blue, red, and near infrared. Out of all the combinations of halides and binding sites that are calculated, we have found that fluorination of the optimum binding site induces a dipole difference between ground and excited states larger than 0.5 D for all three molecules with the highest value of 0.69 D for fluoroperylene. We also report on synthesis of 3-fluoroterrylene and bulk spectroscopy of this compound in liquid and solid organic environments.Comment: Article presented in Faraday Discussions on September 201

SCGG: A Deep Structure-Conditioned Graph Generative Model

Deep learning-based graph generation approaches have remarkable capacities for graph data modeling, allowing them to solve a wide range of real-world problems. Making these methods able to consider different conditions during the generation procedure even increases their effectiveness by empowering them to generate new graph samples that meet the desired criteria. This paper presents a conditional deep graph generation method called SCGG that considers a particular type of structural conditions. Specifically, our proposed SCGG model takes an initial subgraph and autoregressively generates new nodes and their corresponding edges on top of the given conditioning substructure. The architecture of SCGG consists of a graph representation learning network and an autoregressive generative model, which is trained end-to-end. Using this model, we can address graph completion, a rampant and inherently difficult problem of recovering missing nodes and their associated edges of partially observed graphs. Experimental results on both synthetic and real-world datasets demonstrate the superiority of our method compared with state-of-the-art baselines

The Ten-Year Road: Joys and Challenges on the Road to Tenure

This paper explores the pre-tenure experiences of five assistant professors employed in the faculty of education of a research-intensive university. Acting as co-researchers, the authors researched their experiences through a critical narrative approach. The analysis, informed by critically-oriented writing that extends Wenger\u27s Communities of Practice, takes as axiomatic the notion that globalized processes of economic restructuring are mediating work in the academy and examines its local manifestations. Discussions explore issues of power, equity, shifting identities, and the need for improved navigational resources. The authors found that the process of critically and collaboratively researching their pre-tenure experiences offered insight into sites of personal and professional agency and also served as the impetus to form the social semiotic spaces that encouraged a sense of community. The Dean, a tenured member, but also a newcomer, serves in the role of critical friend

An Investigation of the Geometrical Effects on the Thermal Conductivity of Graphene Antidot Lattices

In this work we investigate the thermal conductivity of graphene-based antidot lattices. A third nearest-neighbor tight-binding model and a forth nearest-neighbor force constant model are employed to study the electronic and phononic band structures of graphene-based antidot lattices. Ballistic transport models are used to evaluate the electronic and the thermal conductivities. Methods to reduce the thermal conductivity and to increase the thermoelectric figure of merit of such structures are studied. Our results indicate that triangular antidot lattices have the smallest thermal conductivity due to longer boundaries and the smallest distance between the neighboring dots

Implementation of Open Boundary Problems in Photo-Conductive Antennas by Using Convolutional Perfectly Matched Layers

A method to simulate an open boundary problem within the Finite Differences Time Domain (FDTD) approach for the emission of photo-conductive antennas is presented here. For this purpose we use convolutional perfectly matched layers (CPML). In these devices, the semiconductor region, where transient currents are present in simulation time, is considered to be an ”active” medium. This medium is extended virtually beyond its boundaries or the computational domain limits. We explain in this paper how to simulate the transient state of a semiconductor in a CPML region as well as the potential of the method developed to solve conventional practical applications

Motion-Induced Radiation from a Dynamically Deforming Mirror

A path integral formulation is developed to study the spectrum of radiation from a perfectly reflecting (conducting) surface. It allows us to study arbitrary deformations in space and time. The spectrum is calculated to second order in the height function. For a harmonic traveling wave on the surface, we find many different regimes in which the radiation is restricted to certain directions. It is shown that high frequency photons are emitted in a beam with relatively low angular dispersion whose direction can be controlled by the mechanical deformations of the plate.Comment: 4 pages, 2 eps figues included, final version as appeared in PR

Clinical case of caseous lymphadenitis in a goat: case management

Corynebacterium pseudotuberculosis is the causative agent of caseous lymphadenitis (CLA) a contagious and infectious disease in small ruminants. This report describes a case of CLA in a Boer cross goat infected with Corynebacterium pseudotuberculosis. The manifestation of abscess in the superficial lymph node presented as a mass of approximately 5cm by 5cm in diameter at the base of the ear. The mass was solid and non-movable upon palpation. The mass was incised and the caseous material was aspirated and sent to the bacteriology laboratory where Corynebacterium pseudotuberculosis was isolated. The wound was cleaned and flushed with diluted chlorhexidine and iodine solutions daily. This procedure aids in the complete healing of the wound after a few weeks. However, the agent of the disease persists in the animal in its entire life and culling is recommended to prevent the spread of the disease in the herd