Metrology, molecules and fundamental tests
Organisation/Company: Metrology, molecules and fundamental tests
Department: Laboratoire de Physique des Lasers
Research Field: Physics » Quantum mechanics, Physics » Optics, Physics » Metrology, Physics » Chemical physics
Researcher Profile: First Stage Researcher (R1)
Positions: PhD Positions
Country: France
Application Deadline: 31 Jul 2025 - 23:59 (Europe/Paris)
Type of Contract: Temporary
Job Status: Full-time
Hours Per Week: 37h40
Offer Starting Date: 1 Sep 2025
Is the job funded through the EU Research Framework Programme? Not funded by a EU programme
Is the Job related to staff position within a Research Infrastructure? No
Looking for potential variations of the proton-to-electron mass ratio and other tests of fundamental physics via precision measurements with molecules.
Internship Description:
The PhD student will participate in cutting-edge experiments aimed at ultra-precise measurements of rovibrational molecular transitions and dedicated to measuring/constraining the potential time variation of the proton-to-electron mass ratio ( µ ), a fundamental constant of the standard model ( SM ). Such variations, if detected, would be a signature of physics beyond the SM, providing insights into the nature of dark matter and dark energy. The idea here is to compare molecular spectra of cosmic objects with corresponding laboratory data. The experimental setup is based on quantum cascade lasers ( QCLs ) locked to optical frequency combs, with traceability to primary frequency standards, a breakthrough technology developed at Laboratoire de Physique des Lasers ( LPL ), allowing unprecedented spectroscopic precision in the mid-infrared range.
The PhD will focus on measuring mid-infrared transitions of methanol ( CH3OH ), a molecule known for its enhanced sensitivity to changes in µ . The student will set up and stabilize a new QCL in a spectral region hosting particularly relevant transitions. The work will involve achieving sub-Doppler spectroscopic resolution to reach target laboratory frequency accuracies of ~100 Hz needed for comparisons with astronomical observations . This activity is part of the ANR Ultiµos project, a collaborative effort which seeks to refine current constraints on the possible variation of µ which involves leading research institutions, including Laboratoire Kastler Brossel (LKB, L. Hilico) and MONARIS (C. Janssen) at Sorbonne Université. The three partners of the Ultiµos consortium will collaborate to conduct measurements in methanol and other species such as ammonia (NH3) in different spectral windows, to identify transitions as targets for future Earth/space comparison campaigns, which could further tighten constraints on variations of µ . Other collaborators, such as Vrije Universiteit Amsterdam and Onsala Space Observatory, will provide theoretical and observational/astronomical support to complement the experimental efforts.
The proposed laser technology is also crucial for the ongoing development at LPL of a new-generation molecular clock specifically designed for precision vibrational spectroscopy of cold polyatomic molecules. The student may therefore be involved in first precise spectroscopic measurements on cold molecules produced at ~1 K in a novel cold molecule apparatus. Combining frequency metrology and cold molecule research has the potential to bring even more stringent constraints on a drifting-µ, and opens possibilities for using polyatomic molecules to perform other fundamental tests, including the measurement of the energy difference between enantiomers of a chiral molecule, a signature of parity (left-right symmetry) violation , and a sensitive probe of dark matter.
Funding already secured.
Where to apply E-mail: ******
Requirements Research Field: Physics » Quantum mechanics, Education Level: Master Degree or equivalent
Research Field: Physics » Optics, Education Level: Master Degree or equivalent
Research Field: Physics » Metrology, Education Level: Master Degree or equivalent
Research Field: Physics » Chemical physics, Education Level: Master Degree or equivalent
Skills/Qualifications: The ideal candidate should have a strong foundation in physics or chemical physics, particularly in areas such as spectroscopy, laser physics, molecular physics, and quantum optics. Proficiency in experimental techniques, data analysis, and computational modelling is highly desirable. Creativity, problem-solving skills, and the ability to work both independently and collaboratively in an interdisciplinary environment are also key.
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