A Low-Temperature Tunable Microcavity featuring High Passive Stability and Microwave Integration

TL;DR

This paper introduces a low-temperature, tunable microcavity system with high passive stability and microwave integration, enhancing quantum emitter coupling and photon collection in cryogenic environments.

Contribution

It presents a cryogenic fiber-based microcavity with ultra-stable passive vibration control, large tunability, and microwave integration for improved spin-photon interfaces.

Findings

Achieved 25 pm stability below 10 K in various configurations.

Enabled microwave control of cavity-coupled quantum emitters.

Demonstrated high photon collection efficiency.

Abstract

Open microcavities offer great potential for the exploration and utilization of efficient spin-photon interfaces with Purcell-enhanced quantum emitters thanks to their large spectral and spatial tunability combined with high versatility of sample integration. However, a major challenge for this platform is the sensitivity to cavity length fluctuations in the cryogenic environment, which leads to cavity resonance frequency variations and thereby a lowered averaged Purcell enhancement. This work presents a closed-cycle cryogenic fiber-based microcavity setup, which is in particular designed for a low passive vibration level, while still providing large tunability and flexibility in fiber and sample integration, and high photon collection efficiency from the cavity mode. At temperatures below 10 Kelvin, a stability level of around 25 picometer is reproducibly achieved in different setup configurations, including the extension with microwave control for manipulating the spin of cavity-coupled quantum emitters, enabling a bright photonic interface with optically active qubits.