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Laser Physics Laboratory is affiliated both to CNRS and to University Paris 13. We study the interactions between light and matter.

Our experiments range from the most fundamental aspects of basic science to applied research: quantum physics, atomic and molecular physics, optical devices, biomedical imaging...

The lab is structured into eight experimental research teams, four shops and an administrative department. It is composed of about seventy-five people (10 CNRS full-time researchers, 30 university teaching staff members, a technical staff of 15 people, about 20 PhD students and post-docs), plus several short-term trainees and foreign visitors.

Olivier Gorceix,
Director of laboratory

Sub-Hz frequency-stabilisation of a quantum cascade laser

Figure : Schéma du dispositif expérimentalResearchers from LNE-SYRTE (Observatoire de Paris, CNRS, UPMC Université Paris 6) and from the Metrology, Molecules and Fundamental Tests group of LPL (Université Paris 13 et CNRS) have recently frequency-stabilised a quantum cascade laser operating in the mid-infrared range and have narrowed its line width down to less than a hertz. The obtained stability and precision, 100 times better than the state-of-the-art, allow for very high precision spectroscopic measurements on a variety of molecules.

This work published in Nature Photonics and mentioned in a previous post is now the subject of a news of the Institut de Physique of CNRS that you can read as a pdf.

Find the article on open archive HAL and arXiv database.


A paper from LPL in la Gazette de la Recherche

The Gazette de la Recherche n°12, the Institut Galilée journal, came out recently. It contains a paper on activities of the Atomic Spectroscopy at Interfaces group of LPL. The paper entitled The colour of the “black body” radiation probed with atoms explains how it is possible to probe, by spectroscopy of an atomic vapour, the distortion of the black body law – which describes how a warm body radiates – at short distances from this body.

This paper is available in French here.

Cooling of a Bose-Einstein Condensate by spin distillation

Spin CoolingWe propose and experimentally demonstrate a new cooling mechanism leading to purification of a spinor Bose-Einstein Condensate (BEC). Our scheme starts with a BEC polarized in the lowest energy spin state. Spin excited states are thermally populated by lowering the single particle energy gap set by the magnetic field. Then these spin-excited thermal components are filtered out, which leads to an increase of the BEC fraction. We experimentally demonstrate such cooling for a spin 3 chromium dipolar BEC. Our scheme should be applicable to Na or Rb, with perspective to reach temperatures below 1 nK.

This work is published in Physical Review Letters 115, 243002 (2015) and a preprint is available on arXiv:1505.05098.

EPJ AP Highlight - Slowing dynamics of a supersonic beam

2D imaging of the slowed Ar* supersonic beam for a final velocity vF = 61 m/s. From this image, one can easily extract the beam divergence and the coherence radius with respect to the position and size of the effective source.The present investigation of the slowing dynamics of a supersonic atom beam by a counter-propagating resonant laser light, in other words the dynamics of atoms in a so-called “Zeeman slower”, is characterized by two special features which are: (i) a close coupling between simulations and experiments using a nozzle beam of metastable argon atoms, (ii) the use in the simulations of a Monte-Carlo (MC) scheme aimed at analysing step by step (i.e. subsequent cycles of absorption-emission) the slowing process and describing in a realistic way atom random walks due to the spontaneous emission. It allows us to get calculated 2D images and radial profiles of the slowed beam, in good agreement with experiment. Other important characteristics as angular aperture, velocity spreads, coherence radius (not easy to be measured experimentally), etc. also result from the simulation. Since the 3D atomic motion within the laser field is considered, border effects can be studied, while they were not directly accessible in a simple radiative force model. It is finally shown that the experimental characteristics of the slowed beam are reproduced by the calculated ones, assuming a point- like source. In general a laser beam is an efficient tool to manipulate the atomic motion and its interaction with atoms can be accurately characterized by means of the present MC-code. Actually any configuration combining resonant light and atoms is relevant (provided that the semi-classical approximation is valid), in particular the use of a “pushing” laser to generate a slow atomic beam from a magneto-optical trap is a technique which has been successfully tested with metastable argon atoms. Here again the MC-code has been able to accurately predict the characteristics of the generated beam.

Slowing dynamics of a supersonic beam, simulation and experiments, M. Hamamda, T. Taillandier-Loize, J. Baudon, G. Dutier, F. Perales and M. Ducloy (2015), Eur. Phys. J. Appl. Phys., 71: 30502, DOI 10.1051/epjap/2015150266

Contacts : Gabriel Dutier and Jacques Baudon

See also other news below ...

Science news of the laboratory
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General news of laboratory
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The awards and honors members of the laboratory
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