Microwave Kinetic Inductace Detector (MKIDs) is a inductance-capacitor oscillating circuit  made from superconducting material. superconducting material. The arrival of photons causes  a change in the characteristic frequency and the phase of the circuit. From this change, it is  possible to detect the arrival of the photon, and, with a suitable calibration, to infer its energy.  These detectors can be operated in photon-counting mode and open the possibility to perform spectrophotometry without inserting any dispersive element in the optical path.  MKID frequency multiplexing enables the implementation of arrays comprising several 

thousand pixels, which can be read in parallel by a single reading line. Here, each pixel, or LC circuit, has its own resonant frequency. MKIDs are an innovative detection technology that will open up a wide range of applications in astronomy et astrophysics. Since 2020, we have been developing at Paris Observatory the first instrument in France employing this technology. It is a spectro-photo-imager that will be mainly dedicated to the observation and study of ultra

compact and ultra-faint galaxies in the Local Group. The instrument will use up to four MKID arrays, each with 20 000 pixels, arranged in a mosaic in the focal plane to achieve a field of view of several arcminutes across the sky. Spectrophotometry of the stars in these galaxies will then allow the study of their stellar populations, including their ages and metallicities. 

One of the major challenges in implementing MKID-based instruments concerns currently the readout system, especially when it comes to large arrays where thousands of MKIDs need to be quickly and simultaneously read. This is a major area of research and development. Reading out such a detector requires the generation of a frequency comb probe signal that simultaneously excites all the pixels, then reads them out to detect the events following photon absorption. The prototype of such a system is currently under development at the Laboratoire d'Instrumentation et de Recherche en Astrophysique (LIRA), at Paris Observatory. At this stage, however, it can only read a small number of pixels, around 2000. 

The aim of this thesis is to to study and develop a full system capable of reading a 20,000 pixel array, as developed [1-5] by the Instrumental Research group of the Laboratoire d'étude de l'Univers et des phénomènes eXtrèmes (LUX), also located at Paris Observatory. This readout system will be designed to integrate the instrument, whose fundamental components - including cryostat, optics, cryogenic electronics, etc. - will be available at the start of the thesis. 

The PhD student will be also involved in the physical characterization of the MKID detectors associated with the readout electronics. The results of the measurements will then be fed into the new astrophysical simulator recently set up to test the data processing software. Close interaction with the team in charge of the software embedded in the readout device is required to define the algorithms needed to process and reduce the data as close as possible to the detector. The PhD student is also expected to familiarize himself/herself with the astrophysical context for which the MKIDs are being developed. 

References :

[1] F. Boussaha, J. Hu, P. Nicaise et al., « Photon-counting with single stoichiometric TiN layer-based optical MKIDs ”, Appl. Phys. Lett. 122, 212602 (2023). 

[2] F. Boussaha, S. Beldi et al., “Development of TiN Vacuum‑Gap Capacitor Lumped‑Element Kinetic 

Inductance Detectors”, J. Low Temp. Phys. 199, 994–1003 (2020). 

[3] J. Hu, F. Boussaha, P. Nicaise, C. Chaumont et al., “ Investigation of reflection-based measurements 

of microwave kinetic inductance detectors in the optical bands ”, Appl. Phys. Lett. 124, 242602 (2024). 

https://doi.org/10.1063/5.0207817 ;

[4] P. Nicaise, J. Hu, C. Chaumont, P. Bonifacio, M. Piat, H. Geoffray and F. Boussaha “ Noise analysis and optical response of microwave kinetic inductance detectors with an optical stack ”, Supercond. Sci. Technol., 2024. 

[5] S. Beldi, F. Boussaha, J. Hu, A. Monfardini et al., « High Q-factor near infrared and visible Al2O3 based parallel-plate capacitor kinetic inductance detectors », Optics Express, Vol. 27, No. 9, 13319, Apr. 2019. 

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For more Information about the topics and the co-financial partner (found by the lab!); contact Directeur de thèse - faouzi.boussaha@obspm.fr

Then, prepare a resume, a recent transcript and a reference letter from your M2 supervisor/ engineering school director and you will be ready to apply online  before March 13th, 2026 Midnight Paris time!