Research
Presentation
The small size of the team makes it easy to interact on the daily basis with the colleagues and students involved in the different projects. All useful information is systematically shared or relayed via the group’s mailing list. Whenever necessary, group meeting are organized, and decisions are taken in a collegial manner. Contacts between all group members are permanent; assistance and guidance are provided immediately. All members participate in defining the research strategy through regular discussions. The PhD students of the team share a single office (or offices close-by), which is extremely useful for the cohesion within the group and sharing knowledge, particularly between experimentalists and theoreticians. All members, permanent and non-permanent, participate to group presentations/seminars, and also to broader actions: inter-team workgroups (Quantum Systems WG), thematical workgroups (Quantum Information WG) and team and laboratory seminars.
History of the team
Originally named Cold Atoms (CA), the team has existed since 1994. It specializes in the field of Quantum Chaos and Anderson localization. Classical systems can exhibit chaotic dynamics in the true sense (showing sensitivity to initial conditions). This is closely linked to a nonlinearity in the system, such as that encountered in the collective effects of the magneto-optical trap. Quantum systems described by the Schrödinger equation do not exhibit nonlinearity, and therefore no sensitivity to initial conditions; the term "quantum chaos" therefore refers to the quantum behavior of systems whose classical analogue is chaotic. The advent of Bose-Einstein condensates opened the door to the study of truly chaotic quantum dynamics, as these systems are described by a variant of the nonlinear Schrödinger equation called the Gross-Pitaevskii equation, and can therefore exhibit positive Lyapunov exponents. These lines of research form the background to the activities carried out within our group.
The distinction mentioned above between chaotic systems of cold atoms naturally fit into the structure of the group, which is made up of two teams. Over time, the field of research has diversified. There is also nonlinear optical activity in optical fibers, in collaboration with the PhLAM Photonics team. Still leveraging the "photonics" aspect, there is also a collaboration with IEMN on the theme of quasi-optical communications in the THz domain. These activities have numerous spin-offs, such as the implementation of "doubled telecom" sources for the new experiment currently being developed with a potassium condensate. The AF group has participated very actively in the construction of the CEMPI Labex project (European Centre for Mathematics, Physics and their Interactions) and plays an important role in the activities of this Labex, in particular via the NLSE (Nonlinear Schrödinger Equation) working group bringing together physicists (from the Cold Atoms, Nonlinear Dynamics and Photonics themes) and mathematicians from the Painlevé laboratory.
The group was also involved in the construction of the Cold Atoms Research Group (GDR), created in 2012, which contributes to uniting this community, notably by enabling greater integration between Parisian and provincial teams. For many years (and now as part of the Cold Atoms Research Group), the group has offered training to new doctoral students from across Europe working in the field, by organizing a predoctoral school in Les Houches. The AF group therefore occupies a leading position in the French Cold Atoms landscape. The comprehensive series of studies conducted since 2008 on the Anderson transition in the context of quantum chaos and time-dependent systems has considerably increased its international visibility. Its recent strengthening in terms of human potential, financial support at the local and national levels, and the projects currently underway guarantee the sustainability of this position in a field with very strong national and international competition.