All Associated laboratories


Laboratoire Kastler Brossel

The research activity in the Kastler Brossel laboratory groups involved in First-TF labex aims at achieving accurate determination of fundamental constants and tests of fundamental theories, like QED, gravitation, or the low-energy limit on strong interaction. The collaboration in the framework of First-TF labex is mainly carried by the research axis “Tests of fundamental interactions and metrology”. It is composed of two teams: “Metrology of simple systems and fundamental tests” and “Trapped Ions”. The first team is working on several experiments:

1) ultra-high precision spectroscopy on hydrogen atom; the goal is to improve the uncertainty on the Rydberg constant and the one on the Lamb shift.

2) Precise determination of the radius of the proton charge by spectroscopy of muonic hydrogen.

3) Determination of the fine structure constant a from the measurement of the ration h/M between the Planck constant and atomic mass. The measurement is achieved combining atom interferometry and Bloch oscillations in accelerated optical lattice.

The activities of the second team are:

4) the measurement of the proton-to-electron mass ratio mp/me by laser spectroscopy of ro-vibrational transitions in trapped molecular hydrogen ions and comparison with QED calculations of the transition frequencies

5) new sympathetic cooling protocols for antimatter H+ ions in the frame of the Gbar project.

Contacts FIRST-TF :

Saida GUELLATI-KHELIFA, Mail : guellati(at)

François NEZ, Mail : nez(at)


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