Jeng Yi Lee

Hide the interior region of core-shell nanoparticles with quantum invisible cloaks

By applying the interplay among the nodal points of partial waves, along with the concept of streamline in fluid dynamics for the probability flux, a quantum invisible cloak to the electron transport in a host semiconductor is demonstrated by simultaneously guiding the probability flux outside the core region and keeping the total scattering cross section negligible. As the probability flux vanishes in the interior region, one can embed any material inside a multiple core-shell sphere without affecting physical observables from the outside. Our results reveal the possibility to design a protection shield layer for fragile interior parts from the impact of transports of electrons.

Reexamination of Kerker's conditions by means of the phase diagram

Jeng Yi Lee, Andrey E. Miroshnichenko, and Ray-Kuang Lee∗1, 3, 4 1 Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 300, Taiwan Nonlinear Physics Centre, Research School of Physics and Engineering, The Australian National University, Canberra 2601, Australia Physics Division, National Center for Theoretical Sciences, Hsinchu 300, Taiwan Corresponding author: rklee@ee.nthu.edu.tw (Dated: May 11, 2017)

Phase diagram for passive electromagnetic scatterers.

With the conservation of power, a phase diagram defined by amplitude square and phase of scattering coefficients for each spherical harmonic channel is introduced as a universal map for any passive electromagnetic scatterers. Physically allowable solutions for scattering coefficients in this diagram clearly show power competitions among scattering and absorption. It also illustrates a variety of exotic scattering or absorption phenomena, from resonant scattering, invisible cloaking, to coherent perfect absorber. With electrically small core-shell scatterers as an example, we demonstrate a systematic method to design field-controllable structures based on the allowed trajectories in this diagram. The proposed phase diagram and inverse design can provide tools to design functional electromagnetic devices.

Phase diagram for investigating the scattering properties of passive scatterers

The study of scattering (i.e., how a single receiver or scatterer responds to an external stimulus) is relevant to a wide range of subjects that are, in some way, related to wave physics (e.g., electromagnetic radiation, elastic waves, thermal diffusion, and quantum physics). Inspired by the recent developments of metamaterials and state-of-the-art nano-optical technologies, the design of functional scatterers has attracted much attention over the last decade (both experimentally and theoretically). For instance, unusual scattering states (including invisible cloaking, resonant scattering, coherent perfect absorption, superscattering, and superabsorbers) have been demonstrated when specific materials are used in the configuration of multilayered structures.1–5 Devices in which these scattering states are used have great potential for applications in biochemistry, greenenergy generation, ultrasensitive detection sensors, and optical microscopy. To obtain the exotic electromagnetic properties at a subwavelength scale, however, a variety of specific conditions need to be satisfied and a better understanding of scattering coefficients is thus required. The study of light radiation being scattered from small particles can be traced back to Lord Rayleigh’s explanation for the color of the sky.6 Furthermore, an exact solution for spherical scatterers was derived by Mie and Lorenz more than a century ago.7 This solution is valid for particles with any geometrical size, and for possible permittivity and permeability values. Nonetheless, although a basic understanding of the recently discovered unusual scattering states can be derived from existing scattering theory, a unified understanding of all these exotic states is still lacking. Figure 1. Phase diagram for a passive scatterer defined by the magnitude, jC .TE;TM/ n j, and the phase, .TE;TM/ n , of the transverse electric (TE) and transverse magnetic (TM) modes of electromagnetic radiation (where n denotes the order of the harmonic channel). The colored region represents the allowable solutions of C .TE;TM/ n and the white region represents the forbidden states for passive scatterers. The value (i.e., color) of the contours represents the normalized absorption cross section ( abs) for the TE or TM modes. : Wavelength of electromagnetic radiation.8

Quantum cloakings hide electronic devices

As the modern development of electronic device smaller and smaller, quantum effect would become significant. Thus extending the concept of quantum mechanics into design of new electronic devices becomes more important. Controlling the movement of these electrons plays the central role in this issue. In this work, we propose a new quantum cloaking mechanism which has completely different to the previous work of Liao et al [1]. This mechanism is based on the scattering cancellation and the interplay among the nodal points of partial waves, that one can simultaneously guide the probability flux outside the interior and keep the total scattering cross section negligible. Moreover, we can put any electric devices inside quantum cloaking without affecting outside probability of matter wave. With the analogy between quantum matter waves and classical waves, the concept of our method can be applied in other fields, such as electromagnetic and acoustic systems, etc.