Rossby waves are known for a long time in atmospheric fluid dynamics: they are due to the variation of the Coriolis force with latitude, known as the beta-effect, and are essential to explain climate dynamics. This internship proposal aims at realizing in the lab a quantum analogue of Rossby waves using a unique tool: a superfluid trapped onto a curved surface.
The Bose-Einstein condensate (BEC) group at Laser Physics Laboratory (LPL) has developed a rubidium BEC experiment producing a superfluid degenerate Bose gas confined in a “bubble-like” potential obtained by a combination of magnetic and radio-frequency (rf) fields. The atoms effectively move onto the two-dimensional surface of this bubble and thanks to an effective “anti-gravity” force can explore a significant fraction of it, thus experiencing the effect of surface curvature [1]. Using the real time control over the rf polarization we also demonstrated the ability to induce rotation in such a system, reaching for the first time a supersonic superflow regime [2]. By combining these two methods we aim at controlling for the first time the beta-effect in a superfluid system and observe the quantum analogue of Rossby waves. To this end we will use a non destructive in-situ imaging technique, currently under development in the lab, to record movies of the density waves on the curved surface.
The student will participate in the various steps of the experiment, from running the experiment to the data analysis, and will acquire good knowledge of state-of-the-art atomic physics. S/he will join the BEC group (currently 9 people, including 3 PhD students and 1 post-doc), and have the opportunity to interact with a larger community at LPL gathering the five ultracold atoms experiments. Our group is a member of QuanTiP, a world-leading joint institute gathering all the groups in Paris area in the field of quantum technology.
At the end of the internship the successful candidate will be given the opportunity to apply for a PhD in the group starting in September 2023, see related PhD offer. This PhD will contribute to a new project, funded by ANR, on "vortex superfluid turbulence on a curved surface" at the interface between quantum, nonlinear and atmospheric physics.

[1] Expansion of a quantum gas in a shell trap, Y. Guo, E. Mercado Gutierrez, D. Rey, T. Badr, A. Perrin, L. Longchambon, V. Bagnato, H. Perrin, and R. Dubessy, New J. Phys. 24, 093040 (2022).

[2] Supersonic rotation of a superfluid: a long-lived dynamical ring, Y. Guo, R. Dubessy, M. de Goër de Herve, A. Kumar, T. Badr, A. Perrin, L. Longchambon, and H. Perrin, Phys. Rev. Lett. 124, 025301 (2020).

The general context of this project is the physics of one-dimensional (1D) quantum gases, used in the spirit of quantum simulation. The BEC group at LPL has developed an experiment where ultracold sodium atoms are trapped in the magnetic field created by microwires, on top of an atom chip, in a very elongated confinement. This technology allows to access regimes where the physics of the system can be considered one-dimensional. The long-term goal of the project is to access the strongly-interacting regime of 1D Bose gases, also referred to as the Tonks-Girardeau regime, by controlling the interatomic interaction thanks to a microwave-induced Feshbach resonance.
The magnetic trap alone provides a harmonic confinement. In order to realize a homogeneous 1D Bose gas, for which analytical theoretical predictions are available, we will use in addition a blue-detuned laser (532 nm) in order to produce light walls at the longitudinal edges of the magnetic confinement of the atoms.The goal of the internship consists in designing and characterizing such optical longitudinal confinement.
First, the optical setup allowing to produce two barrier walls by focusing laser beams underneath the atom chip will be designed, with a fine control over their respective positions. This requires a careful optimization of the beam shape since the atoms are confined at 50 µm of the surface of the chip.
Second, the setup will be implemented and its stability characterized. We aim for a fine control over the positioning of the beams and a good day-to-day reproducibility. The setup will be mounted on a separate breadboard which will be installed on the experiment at the end of the internship.

Environment: The intern will be supervised by Aurélien Perrin. In addition to his/her participation in the experiments carried out on the setup, s/he will benefit from weekly bibliography sessions common to all the teams of the laboratory in the field of cold atoms.
Possibility of a PhD: The ANR Grant Mico3, obtained by the team in 2022, comes with a PhD grant. See related PhD offer.