Missions

The post-doc will contribute to the experimental study of the far-from-equilibrium dynamics of a two-dimensional superfluid quantum gas confined in a bubble-shaped trap. In particular, we will seek to identify the emergence of a turbulent regime on this curved surface in a rotating reference frame. The bubble trap is created using an inhomogeneous magnetic field and a radio-frequency field. By adjusting the properties of the radiofrequency field, it is possible to control the spreading of the superfluid on the surface, as well as its speed of rotation, thus opening the way to the study of the effects due to the curvature of the surface on the dynamics of the system. In this context, it is particularly important to study the elementary excitations of the superfluid at the microscopic scale, appearing in the form of quantum vortices, which will be at the heart of the mission of the person recruited.

Activities

The successful candidate will join the Bose-Einstein Condensate Group of the Laboratoire de physique des lasers. His/her objective will be to help set up the experimental tools needed to study the gas dynamics at the microscopic scale. In particular, he/she will work with the team to develop a new high-resolution imaging method for observing vortices directly in the trap. He/She will also be involved in data collection and analysis. The basic technical tools used in this activity are optics, continuous lasers, laser lock systems, ultra-high vacuum systems and computer controlled laboratory equipment.

Skills

Candidates should have a PhD in the field of atom-laser interaction, and excellent experimental skills. Experience in the physics of cold atoms (laser cooling) or stabilized lasers would be a major asset, as would an interest in the physics of quantum gases. The post-doc should also have excellent team-working skills.

Work Context

The superfluidity of quantum gases was observed shortly after their first realization. Rotation of the gas at moderate speeds led to the observation of vortices with quantized circulation. The regime of very high rotational speeds led to the observation of vortex networks some fifteen years ago. Recently, the host team obtained original results exploring the fast rotation regime in a two-dimensional anharmonic trap: the demonstration of a supersonic flow regime and the study of the melting of a vortex lattice activated by thermal fluctuations. In parallel, the group also developed a gravity compensation protocol to control the gas expansion on the curved surface, opening up the possibility of studying curvature effects in a two-dimensional superfluid for the first time.
The activity will take place at the Laboratoire de Physique des Lasers, a joint research unit of the Université Sorbonne Paris Nord and the CNRS. The Bose-Einstein Condensate group (BEC group, see https://bec.lpl.univ-paris13.fr ) has developed two experiments on the dynamics of quantum gases. One of these experiments routinely produces a rubidium quantum gas confined in a bubble-shaped trap, created using magnetic and radiofrequency fields. The resulting potential is extremely smooth and completely controllable in its geometry, enabling the study of the gas's collective modes and its controlled rotation.
An associate professor from Sorbonne Paris Nord University, a CNRS director and two PhD students will be involved in the project. This project is funded by the French National Research Agency, PRC project VORTECS (Vortex turbulence on a curved surface), in collaboration with Serguei Nazarenko (Université de Nice) and the QuantEdu program. The BEC group also includes a CNRS research engineer, a CNRS researcher, a post-doctoral researcher and a doctoral student, mainly involved in the other experimental set-up. The group is part of the laboratory's Quantum Gases axis, which brings together some twenty researchers. In addition to those already mentioned in the context of this project, the BEC team has established collaborations with several experimental and theoretical groups, notably with Anna Minguzzi of the LPMMC in Grenoble, Patrizia Vignolo of the Institut de physique de Nice, Vanderlei Bagnato from the University of Sao Paulo in Brazil, Maxim Olshanii from the University of Massachusetts in Boston, Thorsten Schumm from TUW University in Vienna.