SearcharxivSearch

arXiv subjects

Sung Hun Park

Publications and source records attributed to Sung Hun Park.

2 recordsLinked to original sources

DNA Nanotechnology for Superradiance

Superradiance, first proposed by Dicke in 1954, is a highly efficient quantum light source that differs from conventional spontaneous emission. Unlike typical spontaneous emission, where intensity scales linearly with the number of electric dipoles, superradiance exhibits an intensity that scales quadratically with the number of electric dipoles. Similarly, the decay rate also increases proportionally to the dipole numbers. This collective emission is especially powerful when it manifests as superfluorescence, a physical regime of superradiance where spontaneously emerging coherence is achieved by arranging excited dipoles in the same orientation within a volume much smaller than their emission wavelength. Numerous experimental strategies have been employed to generate superradiance, with one common approach being the use of stochastically formed aggregates of quantum dots and organic dyes. However, the inherent randomness in such systems prevents precise control over the number, spatial distribution, and relative orientation of the emitters. This often leads to non-uniform coupling strengths and parasitic dephasing effects, which make it difficult to predict the resulting quantum emission and limit its use in engineered devices. A deterministic platform that provides precise control over these parameters is therefore essential for realizing the full potential of superradiant systems. Here, we (i) specifically outline the advantages of DNA nanotechnology in tackling this challenge, (ii) discuss the reasons why superradiance has not yet been realized even with the state-of-the art DNA nanotechnology, and (iii) propose potential solutions for overcoming the current limitations.

quant-ph

Achieving Optical Refractive Index of 10-Plus by Colloidal Self-Assembly

This study demonstrates the developments of self-assembled optical metasurfaces to overcome inherent limitations in polarization density (P) within natural materials, which hinder achieving high refractive indices (n) at optical frequencies. The Maxwellian macroscopic description establishes a link between P and n, revealing a static limit in natural materials, restricting n to approximately 4.0 at optical frequencies. Optical metasurfaces, utilizing metallic colloids on a deep-subwavelength scale, offer a solution by unnaturally enhancing n through electric dipolar (ED) resonances. Self-assembly enables the creation of nanometer-scale metallic gaps between metallic nanoparticles (NPs), paving the way for achieving exceptionally high n at optical frequencies. This study focuses on assembling polyhedral gold (Au) NPs into a closely packed monolayer by rationally designing the polymeric ligand to balance attractive and repulsive forces, in that polymeric brush-mediated self-assembly of the close-packed Au NP monolayer is robustly achieved over a large-area. The resulting monolayer of Au nanospheres (NSs), nanooctahedras (NOs), and nanocubes (NCs) exhibits high macroscopic integrity and crystallinity, sufficiently enough for pushing n to record-high regimes. The study underlies the significance of capacitive coupling in achieving an unnaturally high n and explores fine-tuning Au NC size to optimize this coupling. The achieved n of 10.12 at optical frequencies stands as a benchmark, highlighting the potential of polyhedral Au NPs in advancing optical metasurfaces.

physics.optics