Ultracold strontium gas from light transport to simulators and prospect in ultracold molecules

Présenté par David Wilkowski – Associate professor Nanyang Technological University, Singapore UMI 3654 Majulab, Centre for Quantum Technologies (CQT/NUS), Physics and Applied Physics (SPMS/NTU), Centre for Disruptive Photonic Technologies (CDPT/NTU).

 I will present some recent experiments, done on an ultracold gas of strontium atom. In particular, we studied the coherent light transport in the cold atomic ensemble. Here, the latter can be view as a random scattering medium. When the system is excited by a resonant laser beam, cooperative emission occurs in the forward direction which has characteristic time much faster that the single atom emission decay time. This phenomena show interesting similarity with Dicke superradiance.
I will also give two examples of how we use our ultracold atom system as a simulator of complex (interacting) system. The first example concerns the simulation of statistical ensemble subject to long-range  gravitational-like interaction. An interesting situation occurs for two-dimensional systems where a phase transition brings the gas into a collapse phase. A second example is the generation of an effective non-Abelian gauge field which can be view as a generalisation of the Berry phase in systems having SU(2) symmetry.
Finally I will discuss prospect of laser cooling of simple molecules and what new physics can be targeted in contrast to atomic system.