Temperature tunability of quantum emitter - cavity coupling in a photonic wire microcavity with shielded sidewall loss

TL;DR

This paper demonstrates a temperature-tunable quantum emitter-cavity coupling platform using a coated microcavity with significantly enhanced quality factors at low temperatures, enabling strong coupling phenomena like Rabi splitting.

Contribution

The study introduces a novel method of tuning cavity quality factors via temperature control by applying a thin Al coating to microcavities, significantly improving emitter-cavity coupling capabilities.

Findings

Cavity Q can be tuned from hundreds to 2×10^5 by temperature.

Achieved Rabi splitting of 24 GHz at 40 K in a small device.

Enhanced cavity performance comparable to state-of-the-art photonic crystal nanocavities.

Abstract

Recent technological advancements have allowed to implement in solid-state cavity-based devices phenomena of quantum nature such as vacuum Rabi splitting, controllable single photon emission and quantum entanglement. For a sufficiently strong coupling between a quantum emitter and a cavity, large quality factors ($Q$) along with small modal volume ($V_{eff}$) are essential. Here we show that by applying a 5nm Al coating to the sidewalls of a submicrometer-sized Fabry-P\'{e}rot microcavity, the cavity $Q$ can be temperature-tuned from few hundreds at room temperatures to 2$\times$10$^5$ below 30~K. This is achieved by, first, a complete shielding of the sidewall loss with ideally reflecting lateral metallic mirrors and, secondly, a dramatic decrease of the cavity's axial loss for small-sized devices due to the largely off-axis wavevector within the multilayered structure. Our findings offer a novel temperature-tunable platform to study quantum electrodynamical phenomena of emitter-cavity coupling. We demonstrate that a Rabi splitting of 2g=24~GHz (0.142~nm) can be readily achieved at 40~K in a 0.8$\mu$m-sized device, which has an $V_{eff}\approx0.0845~\mu$m$^3$, comparable to best 2D photonic crystal (PhC) nanocavities.