A Compact, Robust, and Tunable Open Microcavity Platform for Solid-State Quantum Electrodynamics

TL;DR

This paper introduces a compact, vibration-resistant open microcavity platform suitable for cryogenic quantum experiments, enabling stable, tunable, and scalable solid-state quantum electrodynamics studies.

Contribution

The authors develop a small, robust mechanical host for open microcavities that maintains high finesse and tunability at cryogenic temperatures without active stabilization.

Findings

Achieved cavity finesse exceeding 1,000 without vibration-induced broadening.

Demonstrated in situ cavity resonance tuning over 3 nm across multiple cooldowns.

Showed strong coupling between InGaAs quantum dots and the microcavity with cooperativity > 1.

Abstract

Open microcavities provide a powerful platform for studying cavity quantum electrodynamics in solid-state systems. However, operating open microcavities at cryogenic temperatures, as required for many solid-state quantum emitters, typically demands bulky and cryostat-specific vibration-mitigation setups. Here we report a compact, robust, and tunable mechanical host for an open microcavity. The complete mechanical assembly fits within a footprint of $1'' \times 1'' \times 0.5''$. Using this mechanical host, we observe no vibration-induced cavity broadening for an open microcavity with finesse exceeding 1,000 without cryostat customization or active locking. The assembly also enables in situ tuning of the cavity resonance over 3 nm, and the resonance of the same cavity remains within this range across multiple cooldowns. To further showcase the capability of this assembly, we demonstrate coupling between an InGaAs quantum dot and an open microcavity with a cooperativity exceeding unity. This platform provides a versatile testbed for fundamental cavity quantum electrodynamics and a scalable route to portable quantum light sources and spin-photon interfaces for quantum repeaters, quantum networks, and photonic quantum computing.