Nanoblocks embedded in L-shaped nanocavity of a plasmonic sensor for best sensor performance

In this work, we proposed a highly sensitive design of a plasmonic sensor which is formed by embedding a periodic array of nanoblocks in L-shaped cavity formed by the metal–insulator–metal waveguide. The nanoblocks are placed in the strong electric field confinement region to further enhance its strength by confining it to a small area. To validate the study, the spectral characteristics of the proposed sensor design is compared to the spectral characteristics of a standard design having the same geometric parameters excluding nanoblocks in the cavity. The study shows that the incorporation of 5 nanoblocks of length 25 nm in the cavity can provide best performance indicators in the form of sensitivity, figure of merit and Q-factor. The sensitivity, figure of merit and Q-factor of the proposed sensor design is 1065 nm/RIU, 251.17 and 343.4 which is significantly higher than the standard L-shape resonator design. The sensor design can be developed with a single fabrication step. Due to the ease of fabrication and the highly responsive nature of the design, it can be used in biomedical applications.

Radiation guided along a cylindrical symmetry system according to the refractive index profile.

We aim at finding, from a purely theoretical analysis, the behavior that the refractive index should have within a cylindrical waveguide so that the radiation entering the system in a definite way is guided through it. Based on the criterion we have set in a previous article applying the Fermat's extremal principle in the framework of the geometrical optics, we depict the radiation confinement regions for refractive index profiles often used in the construction of waveguides, one step, multi-step and parabolic, by drawing upon the Legendre transform space as an intermediate resource in the process. We have also studied the possibility of performing the reverse path: for a wanted confinement region, to find the parameters defining the refractive index profile of the waveguide to be built. We conclude that such a process is possible as long as we know the shape of the profile. Under such restriction, our analysis allows us to deduce the characteristics that the guide should have so that the radiation entering with a given angle and at a certain distance from its axis remains confined. The technique can be used in design processes as a resource to limit the parameters that characterize the system.

Island divertor configuration design for a quasi-axisymmetric stellarator CFQS

A magnetic field configuration of an island divertor for a quasi-axisymmetric stellarator (CFQS) is proposed. The configuration incorporates large islands surrounding the core confinement region. The interface between the core region and the peripheral region of the island divertor is a clear magnetic separatrix similar to a tokamak divertor. The structure of divertor magnetic field lines is very regular without stochasticity and the connection length is sufficiently long for good divertor performance. Such a divertor configuration is produced in the magnetic field configuration for the CFQS device, which is now under construction in China.

Reformation of the Electron Internal Transport Barrier with the Appearance of a Magnetic Island

When realising future fusion reactors, their stationary burning must be maintained and the heat flux to the divertor must be reduced. This essentially requires a stationary internal transport barrier (ITB) plasma with a fast control system. However, the time scale for determining the position of the foot point of an ITB is not clearly understood even though its understanding is indispensable for fast profile control. In this study, the foot point of the electron ITB (eITB) was observed to be reformed at the vicinity of a magnetic island when the island started to form. In addition, the enhanced confinement region was observed to expand during the eITB formation according to the radial movement of the magnetic island toward the outer region. Compared to the time scales of the local heat transport, the faster time scales of the movement of the eITB foot point immediately after island formation (~0.5 ms) suggest the importance of the magnetic island for plasma profile control to maintain stationary burning.

Structural and electronic properties of NaTaO3 cubic nanowires

Sodium tantalate 1-D nanostructures show novel properties due to their edge confinement region, which may be relevant for distinct applications.

A NEW SETUP FOR THE STUDY OF ADSORPTION/DESORPTION PROCESSES AND NANOPARTICLES FORMATION IN POROUS ALUMINA

We present a setup devoted to the study of adsorption and desorption processes of alkali atoms after deposition on a 300 nm thick porous alumina substrate in an Ultra High Vacuum chamber. Rubidium atoms, delivered by a dispenser source, enter the 20-30 nm diameter pores, diffuse in and stick to their walls. A 1 W power laser is used in order to induce detachment and take the atoms back in the vapor phase in a very tight confinement region. The desorbed atoms coming out the sample can be monitored via both a resonant optical detection and an electronic amplifier after ionization. The desorbing laser is also able to promote the formation of Rubidium nanoparticles, as the high Rb vapor density in the pores favors aggregation around nucleation point defects. In this way, the apparatus allows for the study of the fundamental processes related to atom – surface interactions in presence of light as well as of several promising application to nanomaterials.

Interaction of quantum systems with environment in QCD

It is shown that the interaction of quark with the stochastic vacuum of QCD (considered as an environment) leads to the decoherence of quark colour state, associated with the loss of information on the initial quark colour. We propose to consider this process as a reason of the confinement of the quark colour. Asymptotically this leads to confined quarks (fully mixed colourless quark states) in the limit of large distances and time intervals (confinement region) and free coloured quarks in the limit of small distances and time intervals (asymptotic freedom). We propose quantitative characteristics that allow to describe the process of interaction: purity, fidelity, von Neumann entropy, quantum information measure. The cases of two and arbitrary number of quarks are considered, and it is shown that the entanglement in such system disappears in the limit of large distances and time intervals. The process is in good agreement with the known theorems in quantum information theory (no-cloning and no-hiding). We study non-perturbative evolution of the gluon colour states during short time. Fluctuations of gluons are less than those for coherent states. This fact suggests that there gluon squeezed states can arise. Theoretical justification for the occurrence both singe- and two-mode gluon squeezing effects in QCD is given. We show that gluon entangled states which are closely related with two-mode squeezed states of gluon fields can appear at short time non-perturbative evolution by analogy with corresponding photon states in quantum optics.