Quantum electrodynamics in a whispering-gallery microcavity coated with a polymer nanolayer

TL;DR

This paper theoretically investigates high-Q whispering gallery modes in a polymer-coated silica microtoroid, demonstrating enhanced light-matter interaction suitable for quantum electrodynamics and quantum information applications.

Contribution

It introduces a novel approach to enhance cavity QED effects by coating silica microtoroids with a nanolayer, reducing mode volume and shifting electric field maxima outside the silica.

Findings

High-quality whispering gallery modes achieved in coated microtoroids

Significant reduction in mode volume due to nanolayer coating

Enhanced interaction between quantum dots and cavity mode

Abstract

Quasi-transverse-electric and -transverse-magnetic fundamental whispering gallery modes in a polymer-coated silica microtoroid are theoretically investigated and demonstrated to possess very high-quality factors. The existence of a nanometer-thickness layer not only evidently reduces the cavity mode volume but also draws the maximal electric field's position of the mode to the outside of the silica toroid, where single quantum dots or nanocrystals are located. Both effects result in a strongly enhanced coherent interaction between a single dipole (for example, a single defect center in a diamond crystal) and the quantized cavity mode. Since the coated microtoroid is highly feasible and robust in experiments, it may offer an excellent platform to study strong-coupling cavity quantum electrodynamics, quantum information, and quantum computation.