Electrothermal Model of Kinetic Inductance Detectors

TL;DR

This paper presents an electrothermal model for Kinetic Inductance Detectors that accounts for non-equilibrium quasiparticle states, readout power heating, and feedback effects, enabling simulation of complex device behaviors.

Contribution

It introduces a comprehensive electrothermal framework for modeling KIDs, incorporating heating effects, resonance distortion, hysteresis, and noise analysis, which advances understanding of detector dynamics.

Findings

Resonance-curve distortion and hysteresis are explained by the model.

Electrothermal feedback significantly influences detector behavior.

Generation-recombination noise is linked to thermal fluctuations in the system.

Abstract

An electrothermal model of Kinetic Inductance Detectors (KIDs) is described. The non-equilibrium state of the resonator's quasiparticle system is characterized by an effective temperature, which because of readout-power heating is higher than that of the bath. By balancing the flow of energy into the quasiparticle system, it is possible to calculate the steady-state large-signal, small-signal and noise behaviour. Resonance-curve distortion and hysteretic switching appear naturally within the framework. It is shown that an electrothermal feedback process exists, which affects all aspects of behaviour. It is also shown that generation-recombination noise can be interpreted in terms of the thermal fluctuation noise in the effective thermal conductance that links the quasiparticle and phonon systems of the resonator. Because the scheme is based on electrothermal considerations, multiple elements can be added to simulate the behaviour of complex devices, such as resonators on membranes, again taking into account readout power heating.