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ST199 - Fundamental Noise Processes in TES Devices

Fundamental Noise Processes in TES Devices

Massimiliano Galeazzi

Abstract - Microcalorimeters and bolometres are noise-limited devices, therefore, a proper understanding of all noise sources is essential to predict and interpret their performance. In this paper I review the fundamental noise processes contributing to Transition Edge Sensor (TES) microcalorimeters and bolometers and their effect on device performance. In particular, I will start with a simple, monolithic device model, moving to a more complex one involving discrete components, to finally move to today’s more realistic, comprehensive model. In addition to the basic noise contribution (equilibrium Johnson noise and phonon noise), TES are significantly affected by extra noise, which is commonly referred to as “excess noise”. Different fundamental processes have been proposed and investigated to explain the origin of this excess noise, in particular near equilibrium nonlinear Johnson noise, flux-flow noise, and internal thermal fluctuation noise. Experimental evidence shows that all three processes are real and contribute, at different levels, to the TES noise, although different processes become important at different regimes. It is therefore time to archive the term “excess noise”, considering them “fundamental noise processes” instead.

Index Terms - Superconducting device noise, transition edge sensors.

IEEE/CSC & ESAS European Superconductivity News Forum (ESNF), No. 14, October 2010
The published version of this manuscript appeared in IEEE Transactions on Applied Superconductivity 21, Issue 3, 267 - 271 (2011)