Asymmetric comb waveguide for strong interactions between atoms and light

TL;DR

This paper introduces an asymmetric comb waveguide with unique dispersion properties that enables strong atom-light interactions, allowing for efficient trapping and emission of cold atoms near the waveguide.

Contribution

The authors design a novel asymmetric comb waveguide supporting a slow mode with quartic dispersion, enhancing atom-photon coupling and trapping capabilities.

Findings

Cold Rubidium atoms can be trapped 100 nm from the waveguide.

The waveguide achieves a beta factor of 0.88 for emission into guided photons.

The radiative decay rate into the slow mode is ten times larger than free-space decay.

Abstract

Coupling quantum emitters and nanostructures, in particular cold atoms and waveguides, has recently raised a large interest due to unprecedented possibilities of engineering light-matter interactions. However, the implementation of these promising concepts has been hampered by various theoretical and experimental issues. In this work, we propose a new type of periodic dielectric waveguide that provides strong interactions between atoms and guided photons with an unusual dispersion. We design an asymmetric comb waveguide that supports a slow mode with a quartic (instead of quadratic) dispersion and an electric field that extends far into the air cladding for an optimal interaction with atoms. We compute the optical trapping potential formed with two guided modes at frequencies detuned from the atomic transition. We show that cold Rubidium atoms can be trapped as close as 100 nm from the structure in a 1.3-mK-deep potential well. For atoms trapped at this position, the emission into guided photons is largely favored, with a beta factor as high as 0.88 and a radiative decay rate into the slow mode 10 times larger than the free-space decay rate.