We’re excited to share our latest work on absolute gain and added-noise calibration of cryogenic amplification chains.

Accurate characterization of these systems is essential for high-fidelity microwave measurements. Yet, it typically requires a calibrated cryogenic noise source operating at millikelvin temperatures, an expensive and often impractical resource.

In this work, our team demonstrates a simple alternative based on an on-chip heatable attenuator. By comparing DC and RF heating and analyzing the resulting thermal noise power spectral density, the amplification chain itself can be used to obtain an absolute calibration — without any external reference source.

The method dissipates only ~1 nW of power and reaches steady state within a few milliseconds, enabling fast and broadband calibration.

This approach is particularly relevant for near-quantum-limited parametric amplifiers used in superconducting quantum processors and related applications.

Preprint available here: https://arxiv.org/abs/2602.16889