GaAs droplet quantum dots with nanometer-thin capping layer for plasmonic applications

We report on the growth and optical characterisation of droplet GaAs quantum dots with extremely-thin (11 nm) capping layers. To achieve such result, an internal thermal heating step is introduced during the growth and its role in the morphological properties of the quantum dots obtained is investigated via scanning electron and atomic force microscopy. Photoluminescence measurements at cryogenic temperatures show optically stable, sharp and bright emission from single quantum dots, at near-infrared wavelengths. Given the quality of their optical properties and the proximity to the surface, such emitters are ideal candidates for the investigation of near field effects, like the coupling to plasmonic modes, in order to strongly control the directionality of the emission and/or the spontaneous emission rate, crucial parameters for quantum photonic applications.Comment: 1 pages, 3 figure

A Block-based 3D Map: a Crude Sketch of Steric Environment

A 3D map provides useful information for various services. Traditional 3D maps, however, consist of a raw image data and are not suitable for real-time applications. In this paper, we propose a block-based 3D map, which forms three dimensional spaces in a collection of cubic blocks. The block-based 3D map has two major parameters: an object ratio and a block size. The object ratio is defined as the rate of object pixels to air-filled pixels within a block and determines the type of a block. The block size determines actual length of the side of a cubic block and is a matter of resolution and focal distance of images. Experimental results show benefits of the block-based 3D map in reducing sensitivity to noise and in saving amounts of data to be processed. Block-based 3D maps would support a variety of new services by providing additional information to image data in intelligent real-time applications

Mobile Code Anti-Reversing Scheme Based on Bytecode Trapping in ART

As interest in Internet of Things environments rapidly increases throughout the IT convergence field, compatibility with mobile devices must be provided to enable personalized services. The security of mobile platforms and applications is critical because security vulnerabilities of mobile devices can be spread to all things in these environments. Android, the leading open mobile platform, has long used the Dalvik virtual machine as its runtime system. However, it has recently been completely replaced by a new runtime system, namely Android Runtime (ART). The change from Android’s Dalvik to ART means that the existing Dalvik bytecode-based application execution structure has been changed to a machine code-based application execution structure. Consequently, a detailed understanding of ART, such as new file formats and execution switching methods between codes, is required from the viewpoint of application security. In this paper, we demonstrate that an existing Dalvik-based application vulnerability can be exploited as-is in ART. This is because existing Dalvik executable files coexist in the ART executable file, and these Dalvik bytecodes and compiled machine codes have one-to-one mapping relationships. We then propose an ART-based application protection scheme to secure this by dynamically eliminating the one-to-one mapping. In addition, the proposed scheme is implemented to evaluate its reverse engineering resistance and performance through experiments

GaAs droplet quantum dots with nanometer-thin capping layer for plasmonic applications

We report on the growth and optical characterisation of droplet GaAs quantum dots with extremely-thin (11 nm) capping layers. To achieve such result, an internal thermal heating step is introduced during the growth and its role in the morphological properties of the quantum dots obtained is investigated via scanning electron and atomic force microscopy. Photoluminescence measurements at cryogenic temperatures show optically stable, sharp and bright emission from single quantum dots, at near-infrared wavelengths. Given the quality of their optical properties and the proximity to the surface, such emitters are good candidates for the investigation of near field effects, like the coupling to plasmonic modes, in order to strongly control the directionality of the emission and/or the spontaneous emission rate, crucial parameters for quantum photonic applications