Testing Scale Invariance in the lab: Solitons and Breathers for 2D Bose gases

Speaker: Jean Dalibard, College de France

When: April 9, 2021 (Fri), 12:00PM to 01:00PM (add to my calendar)

This event is part of the Biophysics/Condensed Matter Seminar Series.

A fluid is said to be scale-invariant when its interaction and kinetic energies have the same scaling in a dilatation operation. This symmetry, in association with the more general conformal invariance, has profound consequences on the equilibrium properties of the fluid as well as its dynamics. In this talk, I will present recent experimental investigations of scale invariance using a 2D gas of rubidium atoms, whose dynamics is well described by a non-linear Schrödinger (Gross-Pitaevskii) equation. I will show some expected results for this system, such as the observation of 2D solitons, as well as (a priori) unexpected ones such as the existence of breathers, i.e. specific initial shapes that undergo a periodic evolution when placed in a harmonic potential. I will conclude with a possible generalization of such phenomena to other scale invariant fluids.

[1] B. Bakkali-Hassani, C. Maury, Y.-Q. Zou, E. Le Cerf, R. Saint-Jalm, P.C.M. Castilho, S. Nascimbene, J. Dalibard, J. Beugnon, arXiv:2103.0160: Realization of a Townes soliton in a two-component planar Bose gas

[2] R. Saint-Jalm, P.C.M. Castilho, E. Le Cerf, B. Bakkali-Hassani, J.-L. Ville, S. Nascimbene, J. Beugnon, J. Dalibard, Phys. Rev. X 9, 021035 (2019): Dynamical symmetry and breathers in a two-dimensional Bose gas