# A split-cavity design for the incorporation of a DC bias in a 3D microwave cavity

## TL;DR

This paper introduces a split-cavity design that allows for applying a DC bias in a 3D microwave cavity without degrading its quality factor, enabling advanced quantum device integration.

## Contribution

The novel split-cavity architecture enables DC bias application in 3D microwave cavities while preserving high quality factors, demonstrated at room and millikelvin temperatures.

## Key findings

- Successful embedding of a variable capacitance diode for frequency tuning.
- Maintains a high quality factor (~8.8×10^5) at millikelvin temperatures.
- No measurable change in cavity quality factor with DC bias at room temperature.

## Abstract

We report on a technique for applying a DC bias in a 3D microwave cavity. We achieve this by isolating the two halves of the cavity with a dielectric and directly using them as DC electrodes. As a proof of concept, we embed a variable capacitance diode in the cavity and tune the resonant frequency with a DC voltage, demonstrating the incorporation of a DC bias into the 3D cavity with no measurable change in its quality factor at room temperature. We also characterize the architecture at millikelvin temperatures and show that the split cavity design maintains a quality factor $Q_\text{i} \sim 8.8 \times 10^5$, making it promising for future quantum applications.