The group Cold Atoms (CA) was founded in 1994. It is specialized in the field of Quantum Chaos and Anderson localization.
In classical systems a chaotic dynamics in the proper sense (with sensitivity to the initial conditions) is possible. It is intimately linked to a non-linearity of the system, such as that encountered in the collective effects of the magneto-optical trap. Quantum systems are described by Schrödinger’s equation, which does not exhibit nonlinearities, and therefore there is no sensitivity to initial conditions; the term "quantum chaos" therefore refers to the quantum behavior of systems whose classical analog is chaotic.
The advent of Bose-Einstein condensates opened the door to the study of truly chaotic quantum dynamics, these systems being described by a variant of the nonlinear Schrödinger equation called the Gross-Pitaevskii equation, and can thus exhibit positive Lyapunov exonents. These lines of research constitute the backbone of the activities carried out within our group.
The above-mentioned distinction between chaotic systems of cold atoms naturally fell within the structure of the group, consisting of two teams:
Over time, the themes have diversified. There is a non-linear optical activity in optical fibers, in collaboration with PhLAM Photonics team. Still in the "photonic" side, there is also a collaboration with the IEMN on the theme of quasi-optical communications in the THz domain. These activities have numerous spin-offs, for example, the setting up of "doubled telecom" sources for the new experiment of a Potassium condensate under development.
The CA group forms one of the five group of the laboratory; Pascal Szriftgiser is head of the group since January 2014. Within the group, the teams are managed in a rather collegial way, the habit of constructive dialogue having settled well for several years. Because of its still small size and its "geographical" unity within the laboratory, the group has a flexible organization, where exchanges are done through informal discussions. The group regularly organizes seminars with external guests (organizer: Jean-François Clément), which allow to brainstorm ideas and compare them with the guests' points of view.
The CA group participated very actively in the construction of the Labex project CEMPI (European Center for Mathematics, Physics and their Interactions) and plays an important role in the activities of this Labex, in particular via the NLSE group (Nonlinear Schrödinger Equation) bringing together physicists (Cold Atomics, Non Linear Dynamics and Photonics) and mathematicians from the Painlevé laboratory.
The group has also been involved in the construction of the Cold Atoms GDR, created in 2012, and which contributes to federate this community, in particular by allowing an increased integration between the Parisian teams and the provincial teams. For many years (and now in the context of the Cold Atoms GDR), the group offers training to new PhD students from all over Europe, working in the field, by organizing a PréDoctoral school in Les Houches.
The CA group, therefore, has a prominent place in the French cold atom landscape. The very comprehensive series of studies conducted since 2008 on Anderson Transition in the context of quantum chaos and time-dependent systems has significantly increased its international visibility. Its recent strengthening in terms of workforce, the financial support at the local and national level and the projects that are currently developing are the guarantors of the sustainability of this position in a field with strong national and international competition.
Awards and Recognition:
Jean-Claude Garreau: Leconte Prize of the Academy of Sciences (2015)
Daniel Hennequin: Jean Perrin Award for Scientific Popularization, SFP (2013)