Cryogenic coaxial microwave filters

TL;DR

This paper presents the design, fabrication, and testing of cryogenic coaxial microwave filters crucial for quantum experiments at millikelvin temperatures, demonstrating excellent performance and practical application in Josephson junction measurements.

Contribution

It introduces a novel coaxial filter assembly with performance validated against theoretical models, suitable for quantum information and metrology applications at cryogenic temperatures.

Findings

Filter performance matches theoretical predictions

Successful operation in Josephson junction experiments at 15 mK

Demonstrates effectiveness for quantum environment control

Abstract

The careful filtering of microwave electromagnetic radiation is critical for controlling the electromagnetic environment for experiments in solid-state quantum information processing and quantum metrology at millikelvin temperatures. We describe the design and fabrication of a coaxial filter assembly and demonstrate that its performance is in excellent agreement with theoretical modelling. We further perform an indicative test of the operation of the filters by making current-voltage measurements of small, underdamped Josephson junctions at 15 mK.