Postdoctoral Researcher in Quantum Thermometry M/w

**Context**: One of the main current challenges in thermal metrology is to develop practical primary thermometers operational over a wide range of temperatures. The European project JRP PhoQuS-T (Photonic and Quantum Sensors for Practical Integrated Primary Thermometry) aims to develop and validate an innovative primary temperature sensor using quantum technologies. This sensor, based on an optomechanical nanoresonator, consists of a photonic and phononic crystal forming both a mechanical resonator and an optical cavity, coupled through optomechanical interaction. This allows the mechanical (thermal) motion of the resonator to be probed with light. Thermometers based on optomechanical nanoresonators have the potential to overcome the practical complexity of conventional primary thermometers thanks to the possibility of integrating them on a chip and combining the advantages of different techniques (absolute (quantum regime) and relative (classical regime)) to cover a wide range of temperatures. In this project, work will be carried out in close collaboration between three laboratories with expertise in multiple fields. The fabrication of photonic and phononic crystals will take place in the cleanrooms of the Centre de Nanosciences et de Nanotechnologies C2N (Université Paris-Saclay). The quantum protocol will be developed in collaboration with the Optomechanics and Quantum Measurements team at the Kastler Brossel Laboratory LKB (Sorbonne University), and finally, the LNE-Cnam will develop metrological validation methods for the optomechanical thermometer and ensure traceability to the International Temperature Scale. **Missions**: Within the "Temperatures" division of the LNE and with our partners (C2N and LKB), you will contribute to developments in the field of quantum thermometry with the following activities. Based on the initial results obtained during the previous JRP 17FUN05 PhotOQuanT project, new 1D and 2D optomechanical resonators will be developed and tested to reduce the self-heating effect. At the same time, different readout protocols will be improved or developed: photonic thermometry (which explores the frequency shift of optical resonance due to the thermo-optic effect); optomechanical noise thermometry (where the Brownian motion of a mechanical oscillator is probed by optical phase measurement); and quantum correlation thermometry (which uses quantum radiation pressure noise to calibrate the thermal noise of the resonator). Metrological characterization of the developed sensors will be carried out in specially designed low-gradient cryostats equipped with calibrated temperature probes to ensure traceability to existing temperature references. **Your main missions are as follows**: - Participate in the engineering of optomechanical resonators (design, modeling, etc.). - Contribute to the engineering of optical instrumentation (fibered and free-space optical setup), electronic detection (low-noise detection, spectrum analyzer), and signal processing (FPGA, data transfer for post-processing). - Supervise the installation of new cryostats (pulse tube, dilution refrigerator) and verify the performance claimed by the supplier. - Operate and characterize optomechanical resonators over a wide temperature range (1 K - 300 K) and validate their performance as temperature sensors with different techniques: quantum correlation thermometry (below 10 K), optomechanical noise thermometry (1 K - 300 K), and photonic thermometry (50 K - 300 K). - Ensure reporting actions, particularly to European project partners, and promote results through scientific communications and publications. **Profil**: You hold a doctoral degree (Ph.D., Bac+8) in physics and have gained experience in the following fields: optics and photonics, quantum physics, nanofabrication, cryogenics, and signal processing. You have a strong interest in experimental sciences, measurement, instrumentation, and applied and technological research. You possess knowledge of optomechanical systems and demonstrate experience in low-temperature measurements. Experience in data acquisition and processing (Python and LabView, FPGA, rapid data transfer/storage for post-processing) will be highly appreciated. You have analytical and synthesis skills. Pragmatic by nature, you demonstrate rigor, critical thinking, and autonomy. You enjoy teamwork. Proficiency in scientific English is essential for the promotion of your work (writing articles, conferences, meetings) and for collaboration with European project partners. Occasional travel is expected for the scientific exchanges necessary for the mission (project meetings with European partners, international conferences, etc.) in Ile de France, France, Europe, and internationally. **CDD** - 24 mois Saint-Denis (Île-de-France)- Réf. MB/THERQUAN/DMSI