Des premiers lasers à gaz carbonique aux interféromètres atomiques et moléculaires

The objective of this publication is to bring out the common thread that has guided me on a sometimes chaotic path from spectroscopy to atomic interferometry. The search for an ever-increasing resolving power has led spectroscopists to take into account the external motion of atoms and molecules. The usual Doppler broadening and then the relativistic Doppler effect could be accommodated with a classical treatment of this external motion. But the recoil effect has required to introduce explicitly momentum conservation between light and atoms. This has imposed to treat simultaneously internal and external degrees of freedom in a quantum way. The processes involved in the different spectroscopy methods then appeared as quantum interference phenomena between different space-time paths correlated with changes in the internal state of objects. These interferences are well represented by density matrix diagrams. The notion of atomic interferometer is made evident in these diagrams. The Ramsey separate field method can be interpreted as an interferometric process in the internal space of atoms and can be extended to the optical domain through an interference in the external space that cancels out the first-order Doppler effect. The new interferometers are inertial sensors together with clocks, with an external phase added to the internal phase. A unified description is naturally made in a five-dimensional space that combines these two aspects by adding the internal dimension represen...

Source: Comptes Rendus Physique - August 7, 2019 Category: Physics Source Type: research