CONCERTO : Digital processing for finding and tuning LEKIDs

TL;DR

This paper introduces online algorithms for probing and tuning LEKID detectors used in millimeter wavelength astronomy, addressing challenges in readout, calibration, and resonance frequency control for improved observational accuracy.

Contribution

It presents novel online algorithms for identifying and continuously tuning LEKID resonance frequencies, enhancing their performance in astronomical observations.

Findings

Effective automatic resonance frequency control achieved.

Improved calibration and stability of LEKID arrays.

Enhanced suitability for real-time astronomical data acquisition.

Abstract

We describe the on-line algorithms developed to probe Lumped Element Kinetic Inductance Detectors (LEKID) in this paper. LEKIDs are millimeter wavelength detectors for astronomy. LEKID arrays are currently operated in different instruments as: NIKA2 at the IRAM telescope in Spain, KISS at the Teide Observatory telescope in Tenerife, and CONCERTO at the APEX 12-meter telescope in Chile. LEKIDs are superconducting microwave resonators able to detect the incoming light at millimeter wavelengths and they are well adapted for frequency multiplexing (currently up to 360 pixels on a single microwave guide). Nevertheless, their use for astronomical observations requires specific readout and acquisition systems both to deal with the instrumental and multiplexing complexity, and to adapt to the observational requirements (e.g. fast sampling rate, background variations, on-line calibration, photometric accuracy, etc). This paper presents the different steps of treatment from identifying the resonance frequency of each LEKID to the continuous automatic control of drifting LEKID resonance frequencies induced by background variations.