Plasmonic Tamm states: second enhancement of light inside the plasmonic waveguide

A type of Tamm states inside metal-insulator-metal (MIM) waveguides is proposed. An impedance based transfer matrix method is adopted to study and optimize it. With the participation of the plasmonic Tamm states, fields could be enhanced twice: the ffirst is due to the coupling between a normal waveguide and a nanoscaled plasmonic waveguide and the second is due to the strong localization and field enhancement of Tamm states. As shown in our 2D coupling configuration, |E|^2 is enhanced up to 1050 times when 1550 nm light is coupled from an 300 nm Si slab waveguide into an 40 nm MIM waveguide.Comment: 3 pages, 4 figure

Error Mitigated Metasurface-Based Randomized Measurement Schemes

Estimating properties of quantum states via randomized measurements has come to play a significant role in quantum information science. In this paper, we design an innovative approach leveraging metasurfaces to perform randomized measurements on photonic qubits, together with error mitigation techniques that suppress realistic metasurface measurement noise. Through fidelity and purity estimation, we confirm the capability of metasurfaces to implement randomized measurements and the unbiased nature of our error-mitigated estimator. Our findings show the potential of metasurface-based randomized measurement schemes in achieving robust and resource-efficient estimation of quantum state properties

Open and closed conformations of a sub-80 kDa Chagas vaccine candidate defined by a cryo-EM led integrative approach

Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, remains a significant global public health concern. It affects an estimated eight million individuals worldwide, with the majority remaining undiagnosed. Despite its profound health impact in both endemic and non-endemic areas, no vaccine is available, and the existing therapies are outdated, producing severe side effects.The 80kDa prolyl oligopeptidase of Trypanosoma cruzi (TcPOP) has been recently identified as a leading candidate for Chagas vaccine development. However, its three-dimensional structure has remained elusive for almost two decades since its discovery. We report the first three-dimensional structure of TcPOP in open and closed conformation, at a resolution of 3.0 and 2.5 Angstroms respectively, determined using single-particle cryo-electron microscopy. Multiple conformations were observed and were further characterized, using plasmonic optical tweezers.To assess the immunogenic potential of TcPOP, we immunized mice and evaluated both polyclonal and monoclonal responses against the TcPOP antigen and its homologues. The results revealed unexpected cross-reactivity across prolyl POPs from other closely related parasites, but intriguingly, not towards the human homologue.Altogether, our findings provide critical structural insights necessary to understand the immunogenicity of TcPOP for future Chagas vaccine development and diagnostic applications.Additionally, our integrative approach indicated that stage-tilted acquisition can yield biologically relevant information for challenging sub-80kDa proteins and could adequately resolve the cryoEM structures. Consequently, this comprehensive strategy can significantly enhance the success rate in determining the structures of proteins that present challenges in characterization

Third-harmonic generation and imaging with resonant Si membrane metasurface

Dielectric metasurfaces play an increasingly important role in enhancing optical nonlinear generations owing to their ability to support strong light-matter interactions based on Mie-type multipolar resonances. Compared to metasurfaces composed of the periodic arrangement of nanoparticles, inverse, so-called, membrane metasurfaces offer unique possibilities for supporting multipolar resonances, while maintaining small unit cell size, large mode volume and high field enhancement for enhancing nonlinear frequency conversion. Here, we theoretically and experimentally investigate the formation of bound states in the continuum (BICs) from silicon dimer-hole membrane metasurfaces. We demonstrate that our BIC-formed resonance features a strong and tailorable electric near-field confinement inside the silicon membrane films. Furthermore, we show that by tuning the gap between the holes, one can open a leaky channel to transform these regular BICs into quasi-BICs, which can be excited directly under normal plane wave incidence. To prove the capabilities of such metasurfaces, we demonstrate the conversion of an infrared image to the visible range, based on the Third-harmonic generation (THG) process with the resonant membrane metasurfaces. Our results suggest a new paradigm for realising efficient nonlinear photonics metadevices and hold promise for extending the applications of nonlinear structuring surfaces to new types of all-optical near-infrared imaging technologies

Localized Nanopore Fabrication via Controlled Breakdown

Nanopore sensors provide a unique platform to detect individual nucleic acids, proteins, and other biomolecules without the need for fluorescent labeling or chemical modifications. Solid-state nanopores offer the potential to integrate nanopore sensing with other technologies such as field-effect transistors (FETs), optics, plasmonics, and microfluidics, thereby attracting attention to the development of commercial instruments for diagnostics and healthcare applications. Stable nanopores with ideal dimensions are particularly critical for nanopore sensors to be integrated into other sensing devices and provide a high signal-to-noise ratio. Nanopore fabrication, although having benefited largely from the development of sophisticated nanofabrication techniques, remains a challenge in terms of cost, time consumption and accessibility. One of the latest developed methods—controlled breakdown (CBD)—has made the nanopore technique broadly accessible, boosting the use of nanopore sensing in both fundamental research and biomedical applications. Many works have been developed to improve the efficiency and robustness of pore formation by CBD. However, nanopores formed by traditional CBD are randomly positioned in the membrane. To expand nanopore sensing to a wider biomedical application, controlling the localization of nanopores formed by CBD is essential. This article reviews the recent strategies to control the location of nanopores formed by CBD. We discuss the fundamental mechanism and the efforts of different approaches to confine the region of nanopore formation