# A Model for Excess Johnson Noise in Superconducting Transition-edge Sensors

## TL;DR

This paper presents a new model explaining excess Johnson noise in superconducting Transition-Edge Sensors by considering dynamic resistance and Josephson oscillation effects, aligning well with experimental data.

## Contribution

The paper introduces a novel noise model for TES that accounts for excess noise through dynamic resistance and Josephson frequency mixing, improving understanding of TES noise behavior.

## Key findings

- Model accurately predicts excess noise in TES.
- Predictions match experimental measurements.
- Highlights the role of Josephson oscillations in noise.

## Abstract

Transition-Edge Sensors (TESs) are two-dimensional superconducting films used to detect energy or power. TESs are voltage biased in the resistive transition where the film resistance is both finite and a strong function of temperature. Electrical noise is observed in TESs that exceeds the predictions of existing noise theories. In this manuscript, we describe a model for the unexplained excess noise based on the dynamic resistance of the TES and noise mixed down from frequencies around the Josephson oscillations. We derive an expression for the power spectral density of this noise and show that its predictions match measured data.