55,200 research outputs found
Tunable metasurface devices based on soft matter
No full textSoft matter materials constitute an exciting platform to introduce flexibility, versatility and tunability into metasurface devices. Despite the low refractive index of polymers, soft matter materials can be effectively employed either as the base meta-atoms, or in composite with solid-state dielectric nanoresonators, for tunable metasurfaces. In this chapter we introduce the physical mechanisms enabling soft matter-based metasurfaces and provide an overview of the existing platforms for static and dynamic soft matter metasurfaces, including metasurfaces that can be tuned electrochemically, optically and thermally. We also provide an overview of soft matter used in combination with solid-state dielectric metasurfaces to introduce tunability, including as flexible substrates, dynamic coatings and refractive index tuning. We conclude by discussing the key challenges and opportunities for the widespread implementation of soft matter metasurfaces.No Full Tex
Small asymmetric Brownian objects self-align in nanofluidic channels
No full textAlthough the self-alignment of asymmetric macro-sized objects of a few tens of microns in size have been studied extensively in experiments and theory, access to much smaller length scales is still hindered by technical challenges. We combine molecular dynamics and stochastic rotation dynamics techniques to investigate the self-orientation phenomenon at different length scales, ranging from the micron to the nano scale by progressively increasing the relative strength of diffusion over convection. To this end, we model an asymmetric dumbbell particle in Hele-Shaw flow and explore a wide range of Péclet numbers (Pe) and different particle shapes, as characterized by the size ratio of the two dumbbell spheres (R). By independently varying these two parameters we analyse the process of self-orientation and characterize the alignment of the dumbbell with the direction of the fluid flow. We identify three different regimes of strong, weak and no alignment and we map out a state diagram in Pe versus R plane. Based on these results, we estimate dimensional length scales and flow rates for which these findings would be applicable in experiments. Finally, we find that the characteristic reorientation time of the dumbbell is a monotonically decreasing function of the dumbbell anisotropy.Accepted Author ManuscriptComplex Fluid Processin
Nanoelectronics: from droplets to devices
No full textSingle-electron behaviour has been observed in devices that can be made by simply trapping gold nanoparticles between two droplets of liquid metal
Single-Photon Counting with Semiconductor Resonant Tunneling Devices
No full textOptical quantum information science and technologies require the capability to generate, control, and detect single or multiple quanta of light. The need to detect individual photons has motivated the development of a variety of novel and refined single-photon detectors (SPDs) with enhanced detector performance. Superconducting nanowire single-photon detectors (SNSPDs) and single-photon avalanche diodes (SPADs) are the top-performer in this field, but alternative promising and innovative devices are emerging. In this review article, we discuss the current state-of-the-art of one such alternative device capable of single-photon counting: the resonant tunneling diode (RTD) single-photon detector. Due to their peculiar photodetection mechanism and current-voltage characteristic with a region of negative differential conductance, RTD single-photon detectors provide, theoretically, several advantages over conventional SPDs, such as an inherently deadtime-free photon-number resolution at elevated temperatures, while offering low dark counts, a low timing jitter, and multiple photon detection modes. This review article brings together our previous studies and current experimental results. We focus on the current limitations of RTD-SPDs and provide detailed design and parameter variations to be potentially employed in next-generation RTD-SPD to improve the figure of merits of these alternative single-photon counting devices. The single-photon detection capability of RTDs without quantum dots is shown
Semiclassical magnetotransport in strongly spin-orbit coupled Rashba two-dimensional electron systems
No full textSemiclassical magnetoelectric and magnetothermoelectric transport in strongly spin-orbit coupled Rashba two-dimensional electron systems is investigated. In the presence of a perpendicular classically weak magnetic field and short-range impurity scattering, we solve the linearized Boltzmann equation self-consistently. Using the solution, it is found that when Fermi energy EF locates below the band crossing point (BCP), the Hall coefficient is a nonmonotonic function of electron density ne and not inversely proportional to ne. While the magnetoresistance (MR) and Nernst coefficient vanish when EF locates above the BCP, non-zero MR and enhanced Nernst coefficient emerge when EF decreases below the BCP. Both of them are nonmonotonic functions of EF below the BCP. The different semiclassical magnetotransport behaviors between the two sides of the BCP can be helpful to experimental identifications of the band valley regime and topological change of Fermi surface in considered systems.National Natural Science Foundation of China [11274018]SCI(E)[email protected]
Electrochemical kinetics of hydrogen intercalation in gadolinium switchable mirrors
No full textPotential-step experiments on gadolinium thin-film electrodes provide current and optical transmission transients, whose time constants are related to effective hydrogen diffusion coefficients according to a standard diffusion model. The diffusion coefficients and switching kinetics depend on temperature, hydrogen concentration, potential, and film thickness. A thickness dependence of the kinetics is observed in which the diffusion coefficient and optical switching time are linearly dependent. (C) 2003 American Institute of Physics
- …
