Mirror, mirror trap the light: Measuring invisible light waves via electro-optic cavities

Key Aspects

• Electro-Optic Cavities: Enable in-situ measurement of intra-cavity electric fields.
• Terahertz Spectral Range: Focus on low-energy interactions of quasi-particles in solids and molecules, e.g. crucial for understanding quantum dynamics in correlated materials.
• Hybrid Cavity Design: Development of a tunable multi-layer cavity design providing an ON-OFF switch for light-matter interaction.
• Theoretical Insights: New models explaining complex interplay of electromagnetic modes and how to distinguish light-matter quasi-particles (polaritons) in future.

Introduction to Electro-Optic Cavities

In a significant advancement in the field of cavity electrodynamics, the team of physicists have introduced a novel method to measure electric fields inside cavities. By utilizing electro-optic Fabry-Pérot resonators, they have achieved sub-cycle timescale measurements, allowing for insight into light and matter, exactly where their interaction takes place.

Focus on the Terahertz Spectral Range

Cavity electrodynamics explores how materials placed between mirrors interact with light, altering both their properties and dynamic behavior. This study focuses on the terahertz (THz) spectral range, where low-energy excitations dictate the fundamental material properties. The ability to measure novel states, which simultaneously behave like light and matter excitations, within the cavity will provide a clearer understanding of these interactions.

Innovative Hybrid Cavity Design

The researchers have also developed a hybrid cavity design, incorporating a tunable air gap with a split detector crystal within the cavity. This new design allows for precise control over internal reflections, leading to selective interference patterns on-demand. These observations are supported by mathematical models, providing a key to decode the complicated cavity dispersion and a deeper understanding of the underlying physics.

Future Implications

This research lays the groundwork for future studies in cavity light-matter interactions, offering potential applications for quantum computing, material science, and beyond. Michael S. Spencer, first author of the study noted, "Our work opens new possibilities for exploring and steering the fundamental interactions between light and matter, providing a unique toolset for future scientific discoveries." Prof. Dr. Sebastian Maehrlein, the leader of the research group, summarizes, "Our EOCs provide a highly-accurate field-resolved view, inspiring novel pathways for cavity quantum electrodynamics in experiment and theory."